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Several [[hormone]]s have been linked to acne: the androgens [[testosterone]], [[dihydrotestosterone]] (DHT) and [[dehydroepiandrosterone|dehydroepiandrosterone sulfate]] (DHEAS), as well as [[insulin-like growth factor 1]] (IGF-I).
Several [[hormone]]s have been linked to acne: the androgens [[testosterone]], [[dihydrotestosterone]] (DHT) and [[dehydroepiandrosterone|dehydroepiandrosterone sulfate]] (DHEAS), as well as [[insulin-like growth factor 1]] (IGF-I).


Development of acne vulgaris in later years is uncommon, although this is the age group for [[rosacea]], which may have similar appearances. True acne vulgaris in adult women may be a feature of an underlying condition such as pregnancy and disorders such as [[polycystic ovary syndrome]] or the rare [[Cushing's syndrome]]. Menopause-associated acne occurs as production of the natural anti-acne ovarian hormone [[estradiol]] fails at menopause. The lack of estradiol also causes thinning hair, hot flushes, thin skin, wrinkles, vaginal dryness, and predisposes to osteopenia and osteoporosis as well as triggering acne (known as acne climacterica in this situation).
Development of acne vulgaris in later years is uncommon, although this is the age group for [[rosacea]], which may have similar appearances. True acne vulgaris in adult women may be a feature of an underlying condition such as pregnancy and disorders such as [[polycystic ovary syndrome]] or the rare [[Cushing's syndrome]]. Menopause-associated acne occurs as production of the natural anti-acne ovarian hormone [[estradiol]] fails at menopause. The lack of estradiol also causes thinning hair, hot flushes, thin skin, wrinkles, vaginal dryness, and predisposes to osteopenia and osteoporosis as well as triggering acne (known as acne climacterica in this situation). [http://traditionalindianherbs.com/hormonal-acne-treatment.html Hormonal Acne Treatment] is also available now a days.


===Genetic===
===Genetic===

Revision as of 11:16, 28 November 2012

This article is about a skin disease commonly found during adolescence. For other acneform skin diseases, see Acne (disambiguation).
Acne
SpecialtyDermatology, family medicine Edit this on Wikidata

Acne vulgaris (cystic acne or simply acne) is a common human skin disease, characterized by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and possibly scarring.[1] Acne affects mostly skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back. Severe acne is inflammatory, but acne can also manifest in noninflammatory forms.[2] The lesions are caused by changes in pilosebaceous units, skin structures consisting of a hair follicle and its associated sebaceous gland, changes that require androgen stimulation.

Acne occurs most commonly during adolescence, and often continues into adulthood. In adolescence, acne is usually caused by an increase in testosterone, which accrues during puberty, regardless of sex.[3] For most people, acne diminishes over time and tends to disappear — or at the very least decreases — by age 25.[4] There is, however, no way to predict how long it will take to disappear entirely, and some individuals will carry this condition well into their thirties, forties, and beyond.[5]

Some of the large nodules were previously called "cysts" and the term nodulocystic has been used to describe severe cases of inflammatory acne.[6] The "cysts," or boils that accompany cystic acne, can appear on the buttocks, groin, and armpit area, and anywhere else where sweat collects in hair follicles and perspiration ducts.[7] Cystic acne affects deeper skin tissue than does common acne.[8]

Aside from scarring, its main effects are psychological, such as reduced self-esteem[9] and in very extreme cases, depression or suicide.[10] Acne usually appears during adolescence, when people already tend to be most socially insecure. Early and aggressive treatment is therefore advocated by some to lessen the overall long-term impact to individuals.[9]

Terminology

The term acne comes from a mutation of the Greek ἀκμή (akmē), literally "point, edge", but in the sense of a "skin eruption"[11] in the writings of Aëtius Amidenus. Used by itself, the term "acne" refers to the presence of pustules and papules.[12] The most common form of acne is known as acne vulgaris, meaning "common acne". Many teenagers get this type of acne. Use of the term "acne vulgaris" implies the presence of comedones.[13]

The term "acne rosacea" is a synonym for rosacea, however some individuals may have almost no acne comedones associated with their rosacea and therefore prefer the term rosacea.[14] Chloracne is associated with exposure to polyhalogenated compounds.

Signs and symptoms

Typical features of acne include: seborrhea (increased oil-sebum secretion), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and, possibly scarring.[1] The appearance of acne varies with skin color.

Scars

Acne scars are the result of inflammation within the dermis brought on by acne. The scar is created by the wound trying to heal itself resulting in too much collagen in one spot.[15]

Physical acne scars are often referred to as "Icepick" scars. This is because the scars tend to cause an indentation in the skin's surface. There are a range of treatments available. Although quite rare, the medical condition Atrophia Maculosa Varioliformis Cutis also results in "acne-like" depressed scars on the face.

  • Ice pick scars: Deep pits, that are the most common and a classic sign of acne scarring.
  • Box car scars: Angular scars that usually occur on the temple and cheeks, and can be either superficial or deep, these are similar to chickenpox scars.
  • Rolling scars: Scars that give the skin a wave-like appearance.
  • Hypertrophic scars: Thickened, or keloid scars.

Pigmentation

Pigmented scars is a slightly misleading term, as it suggests a change in the skin's pigmentation and that they are true scars; however, neither is true. Pigmented scars are usually the result of nodular or cystic acne (the painful 'bumps' lying under the skin). They often leave behind an inflamed red mark. Often, the pigmentation scars can be avoided simply by avoiding aggravation of the nodule or cyst. Pigmentation scars nearly always fade with time taking between three months to two years to do so, although can last indefinitely if untreated.

  • A severe case of cystic acne
    A severe case of cystic acne
  • Cystic acne on the back.
    Cystic acne on the back.
  • Different types of Acne Vulgaris: A: Cystic acne on the face, B: Subsiding tropical acne of trunk, C: Extensive acne on chest and shoulders.
    Different types of Acne Vulgaris: A: Cystic acne on the face, B: Subsiding tropical acne of trunk, C: Extensive acne on chest and shoulders.

Cause

Acne develops as a result of blockages in the follicles. Hyperkeratinization and formation of a plug of keratin and sebum (a microcomedo) is the earliest change. Enlargement of sebaceous glands and an increase in sebum production occur with increased androgen (DHEA-S) production at adrenarche. The microcomedo may enlarge to form an open comedone (blackhead) or closed comedone (milia). Comedones are the direct result of sebaceous glands' becoming clogged with sebum, a naturally occurring oil, and dead skin cells. In these conditions, the naturally occurring largely commensal bacterium Propionibacterium acnes can cause inflammation, leading to inflammatory lesions (papules, infected pustules, or nodules) in the dermis around the microcomedo or comedone, which results in redness and may result in scarring or hyperpigmentation.[16]

Hormonal

Hormonal activity, such as menstrual cycles and puberty, may contribute to the formation of acne. During puberty, an increase in male sex hormones called androgens cause the follicular glands to grow larger and make more sebum.[17] Use of anabolic steroids may have a similar effect.[18] Several hormones have been linked to acne: the androgens testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS), as well as insulin-like growth factor 1 (IGF-I).

Development of acne vulgaris in later years is uncommon, although this is the age group for rosacea, which may have similar appearances. True acne vulgaris in adult women may be a feature of an underlying condition such as pregnancy and disorders such as polycystic ovary syndrome or the rare Cushing's syndrome. Menopause-associated acne occurs as production of the natural anti-acne ovarian hormone estradiol fails at menopause. The lack of estradiol also causes thinning hair, hot flushes, thin skin, wrinkles, vaginal dryness, and predisposes to osteopenia and osteoporosis as well as triggering acne (known as acne climacterica in this situation). Hormonal Acne Treatment is also available now a days.

Genetic

The tendency to develop acne runs in families. For example, school aged boys with acne often have other members in their family with acne. A family history of acne is associated with an earlier occurrence of acne and an increased number of retentional acne lesions.[19]

Psychological

While the connection between acne and stress has been debated, scientific research indicates that "increased acne severity" is "significantly associated with increased stress levels."[20] The National Institutes of Health (USA) list stress as a factor that "can cause an acne flare."[21] A study of adolescents in Singapore "observed a statistically significant positive correlation […] between stress levels and severity of acne."[22] It is also not clear whether acne causes stress and thus perpetuates itself to some extent.

Infectious

Propionibacterium acnes (P. acnes) is the anaerobic bacterium species that is widely concluded to cause acne, though Staphylococcus epidermidis has been universally discovered to play some role since normal pores appear colonized only by P. acnes.[23] Regardless, there are specific clonal sub-strains of P. acnes associated with normal skin health and others with long-term acne problems. It is as yet inconclusive whether any of these undesirable strains evolve on-site in the adverse conditions or are all pathogenically acquired, or possibly either depending on the individual patient. These strains either have the capability of changing, perpetuating, or adapting to, the abnormal cycle of inflammation, oil production, and inadequate sloughing activities of acne pores. At least one particularly virulent strain, though, has been circulating around Europe for at least 87 years.[24] In vitro, resistance of P. acnes to commonly used antibiotics has been increasing, as well.[25]

Diet

A high glycemic load diet is associated with worsening acne.[26][27] There is also a positive association between the consumption of milk and a greater rate and severity of acne.[26][28] Other associations such as chocolate and salt are not supported by the evidence.[26] However, chocolate contains a varying amount of sugar that can lead to a high glycemic load, and it can be made with or without milk in one form or another (see types of chocolate).

Diagnosis

There are multiple grading scales for grading the severity of acne vulgaris,[29] three of these being:

  • Leeds acne grading technique: Counts and categorises lesions into inflammatory and non-inflammatory (ranges from 0–10.0).
  • Cook's acne grading scale: Uses photographs to grade severity from 0 to 8 (0 being the least severe and 8 being the most severe).
  • Pillsbury scale: Simply classifies the severity of the acne from 1 (least severe) to 4 (most severe).

Differential

Management

Benzoyl peroxide cream.

Many different treatments exist for acne including benzoyl peroxide, antibiotics, retinoids, antiseborrheic medications, anti-androgen medications, hormonal treatments, salicylic acid, alpha hydroxy acid, azelaic acid, nicotinamide, and keratolytic soaps.[30] They are believed to work in at least 4 different ways, including: normalising shedding into the pore to prevent blockage, killing Propionibacterium acnes, anti-inflammatory effects, hormonal manipulation.[citation needed]

Medications

Benzoyl peroxide

Benzoyl peroxide is a first-line treatment for mild and moderate acne vulgaris due to its effectiveness and mild side-effects (primarily an irritant dermatitis). It works against the "P. acnes" bacterium, and normally causes just dryness of the skin, slight redness, and occasional peeling when side effects occur.[31] This topical does increase sensitivity to the sun as indicated on the package, so sunscreen should be used during the treatment to prevent sunburn. Benzoyl peroxide has been found to be nearly as effective as antibiotics with all concentrations 2.5%, 5.0%, and 10% equally effective.[31] Unlike antibiotics, benzoyl peroxide does not appear to generate bacterial resistance.[31]

Antiseptics

Sometimes benzoyl peroxide topical medication is combined with a salt of hydroxyquinoline, such as potassium hydroxyquinoline sulphate, which has antibacterial properties. One such topical product is available without prescription in the UK.

Antibiotics

Antibiotics are reserved for more severe cases.[31] With increasing resistance of P. acnes worldwide, they are becoming less effective.[31] Commonly used antibiotics, either applied topically or taken orally, include erythromycin, clindamycin, and tetracyclines such as minocycline.

Hormones

In females, acne can be improved with hormonal treatments. The common combined estrogen/progestogen methods of hormonal contraception have some effect, but the antiandrogen cyproterone in combination with an oestrogen (Diane 35) is particularly effective at reducing androgenic hormone levels. Diane-35 is not available in the USA, but a newer oral contraceptive containing the progestin drospirenone is now available with fewer side effects than Diane 35 / Dianette. Both can be used where blood tests show abnormally high levels of androgens, but are effective even when this is not the case. Along with this, treatment with low-dose spironolactone can have anti-androgenetic properties, especially in patients with polycystic ovarian syndrome.

Topical retinoids

Topical retinoids are medications that normalize the follicle cell life cycle. This class includes tretinoin (Retin-A), adapalene (Differin), and tazarotene (Tazorac). Like isotretinoin, they are related to vitamin A, but they are administered topically and they generally have much milder side effects. They can, however, cause significant irritation of the skin. The retinoids appear to influence the cell life cycle in the follicle lining. This helps prevent the hyperkeratinization of these cells that can create a blockage. Retinol, a form of vitamin A, has similar, but milder, effects and is used in many over-the-counter moisturizers and other topical products. Effective topical retinoids have been in use for over 30 years, but are available only on prescription, so are not as widely used as the other topical treatments. Topical retinoids often cause an initial flare-up of acne and facial flushing.

Oral retinoids

A daily oral intake of vitamin A derivative isotretinoin (marketed as Roaccutane, Accutane, Amnesteem, Sotret, Claravis, Clarus) over a period of 4–6 months can cause long-term resolution or reduction of acne. It is believed that isotretinoin works primarily by reducing the secretion of oils from the glands, but some studies suggest that it affects other acne-related factors as well. Isotretinoin has been shown to be very effective in treating severe acne and can either improve or clear well over 80% of patients. The drug has a much longer effect than antibacterial treatments and will often cure acne for good. The treatment requires close medical supervision by a dermatologist because the drug has many known side effects (many of which can be severe). About 25% of patients relapse after one treatment. In those cases, a second treatment for another 4–6 months may be indicated to obtain desired results. It is often recommended that one let a few months pass between the two treatments, because the condition can actually improve somewhat in the time after stopping the treatment and waiting a few months also gives the body a chance to recover. On occasion, a third or even a fourth course is used, but the benefits are often less substantial. The most common side effects are dry skin and occasional nosebleeds (secondary to dry nasal mucosa). Oral retinoids also often cause an initial flare-up of acne within a month or so, which can be severe. There are reports that the drug has damaged the liver of patients. For this reason, it is recommended that patients have blood samples taken and examined before and during treatment. In some cases, treatment is terminated or reduced due to elevated liver enzymes in the blood, which might be related to liver damage. Others claim that the reports of permanent damage to the liver are unsubstantiated, and routine testing is considered unnecessary by some dermatologists. Blood triglycerides also need to be monitored. However, routine testing is part of the official guidelines for the use of the drug in many countries. Some press reports [weasel words] suggest that isotretinoin may cause depression, but, as of September 2005, there is no agreement in the medical literature as to the risk. The drug also causes birth defects if women become pregnant while taking it or take it while pregnant. For this reason, female patients are required to use two separate forms of birth control or vow abstinence while on the drug. Because of this, the drug is supposed to be given to females as a last resort after milder treatments have proven insufficient. Restrictive rules (see iPledge program) for use were put into force in the USA beginning in March 2006 to prevent misuse, causing occasioned widespread editorial comment.[32]

Anti-inflammatories

Nicotinamide, (vitamin B3) used topically in the form of a gel, has been shown in a 1995 study to be of comparable efficacy to topical clindamycin used for comparison.[33] The benefit of topical nicotinamide seems to lie in its anti-inflammatory nature. It is also purported to result in increased synthesis of collagen, keratin, involucrin and flaggrin. According to a cosmetic company, it may be useful for reducing skin hyperpigmentation (dark acne marks), increasing skin moisture and reducing fine wrinkles.[34]. Topical clindamycin is used to treat acne. Clindamycin is in a class of medications called lincomycin antibiotics. It works by slowing or stopping the growth of bacteria that cause acne and by decreasing swelling. It is only for use on the skin.[35] Clindamycin should be applied to freshly cleansed skin; it is best to wait 2-5 minutes after cleansing to apply the product. Once applied, it is beneficial to wait 2-5 minutes before applying moisturizer, sunscreen, or makeup. This will allow the product to adequately absorb into the skin for maximum benefits. Additionally, an oil-free, non-comedogenic moisturizer or sunscreen should be applied after the clindamycin.

Ibuprofen is used in combination with tetracycline[36] for some moderate acne cases.

Mandelic acid has been noted to be an effective topical treatment for mild to moderate acne. It is considered to be a gentler alternative to popular alpha hydroxy acids such as glycolic acid and lactic acid.[37]

Procedures

Dermabrasion

Dermabrasion is a cosmetic medical procedure in which the surface of the skin is removed by abrasion (sanding). It is used to remove sun-damaged skin and to remove or lessen scars and dark spots on the skin. The procedure is very painful and usually requires a general anaesthetic or "twilight anaesthesia", in which the patient is still partly conscious.[5] Afterward, the skin is very red and raw-looking, and it takes several months for the skin to regrow and heal. Dermabrasion is useful for scar removal when the scar is raised above the surrounding skin, but is less effective with sunken scars.

In the past, dermabrasion was done using a small, sterilized, electric sander. In the past decade, it has become more common to use laser dermabrasion using CO2, Er:YAG laser or a combination of both for the treatment of acne scars. Indications for CO2 laser treatment include previous non erythematous and non-proliferative hypertrophic scars, atrophic acne scars and burn scars.[38] Laser dermabrasion is much easier to control, much easier to gauge, and is practically bloodless compared to classic dermabrasion.

Phototherapy

Blue and red light

Light exposure has long been used as a short-term treatment for acne. Recently, visible light has been successfully employed to treat mild to moderate acne (phototherapy or deep penetrating light therapy) - in particular intense violet light (405–420 nm) generated by purpose-built fluorescent lighting, dichroic bulbs, LEDs or lasers. Used twice weekly, this has been shown to reduce the number of acne lesions by about 64%[39] and is even more effective when applied daily. The mechanism appears to be that a porphyrin (Coproporphyrin III) produced within P. acnes generates free radicals when irradiated by 420 nm and shorter wavelengths of light.[40] Particularly when applied over several days, these free radicals ultimately kill the bacteria.[41] Since porphyrins are not otherwise present in skin, and no UV light is employed, it appears to be safe, and has been cleared for marketing by the U.S. FDA.[42][43]

It seems that the treatment works even better if used with a mixture of the violet light and red visible light (660 nanometer), resulting in a 76% reduction of lesions after three months of daily treatment for 80% of the patients;[44] and overall clearance was similar or better than benzoyl peroxide. Unlike most of the other treatments, few if any negative side-effects are typically experienced, and the development of bacterial resistance to the treatment seems very unlikely. After treatment, clearance can be longer-lived than is typical with topical or oral antibiotic treatments; several months is not uncommon. The equipment or treatment, however, is relatively new and reasonably expensive to buy initially, although the total cost of ownership can be similar to many other treatment methods (such as the total cost of benzoyl peroxide, moisturizer, washes) over a couple of years of use.

Photodynamic therapy

In addition, basic science and clinical work by dermatologists Yoram Harth and Alan Shalita and others have produced evidence that intense blue/violet light (405–425 nanometer) can decrease the number of inflammatory acne lesion by 60–70% in four weeks of therapy, in particular, when the P. acnes is pretreated with delta-aminolevulinic acid (ALA), which increases the production of porphyrins. However this photodynamic therapy is controversial and not published in a peer-reviewed journal. A phase II trial, while it showed improvement occurred, failed to show improved response compared to the blue/violet light alone.[45]

In May 2012 Photocure announced a successful fase IIb study with Visonac. Visonac is intended to treat moderate to severe acne. Visonac combines the application of Visonac cream with the active ingredient methyl aminolevulinate 80 mg/g and controlled illumination by a red light source. Visonac showed a statistically significant reduction in inflammatory lesions and overall improvement in acne severity. Visonac is expected to enter phase III early in 2013.[46] Visonac is based on the accumulation of a photosensitizer in the target cells that upon illumination generate reactive oxygen species, killing the cells. The mechanism of action appears to involve killing of bacteria as well as specific action on sebaceous glands and inflammatory cells. The Visonac cream is applied to the acne area, and after a short incubation time, the skin is illuminated with a red light dose of 37J/cm2.[47]

Laser treatment

Laser surgery has been in use for some time to reduce the scars left behind by acne,[48] but research has been done on lasers for prevention of acne formation itself. The laser is used to produce one of the following effects:

  • to burn away the follicle sac from which the hair grows
  • to burn away the sebaceous gland, which produces the oil
  • to induce formation of oxygen in the bacteria, killing them

Since lasers and intense pulsed light sources cause thermal damage to the skin, there are concerns that laser or intense pulsed light treatments for acne will induce hyperpigmented macules (spots) or cause long-term dryness of the skin.

The FDA has approved the use of a cosmetic laser for the treatment of acne. However, efficacy studies have used very small sample sizes for periods of six months or less, and have shown contradictory results.[49] Also, laser treatment being relatively new, protocols remain subject to experimentation and revision,[50] and treatment can be quite expensive. Also, some Smoothbeam laser devices had to be recalled due to coolant failure, which resulted in painful burn injuries to patients.[51]

Surgery

For people with cystic acne, boils can be drained through surgical lancing.[8]

Alternative medicine

Alternative medicine for acne generally claims to cleanse the blood of toxins, increase immunity, balance hormones and sebum production.

  • Tea tree oil (melaleuca oil) has been used with some success, where it is comparable to benzoyl peroxide but without excessive drying, kills P. acnes, and has been shown to be an effective anti-inflammatory in skin infections.[53][54][55]
  • Aloe vera: there are treatments for acne mentioned in Ayurveda using herbs such as Aloe vera. However, scientific evidence for the cosmetic effectiveness of Aloe vera is limited and when present is frequently contradictory.[53][56][57]

Prognosis

Acne usually improves around the age of 20 but may persist into adulthood.[30]

Epidemiology

Acne affects 40 to 50 million people in the United States (16%), and approximately 3 to 5 million in Australia (23%).[58] It affects people of all ethnic groups.[59]

History

Research

A vaccine against inflammatory acne has been tested successfully in mice, but it is not certain that it would work similarly in humans.[64]

A 2007 microbiology article reporting the first genome sequencing of a Propionibacterium acnes bacteriophage (PA6) said this "should greatly enhance the development of a potential bacteriophage therapy to treat acne and, therefore, overcome the significant problems associated with long-term antibiotic therapy and bacterial resistance."[65]

References

  1. ^ a b Adityan B, Kumari R, Thappa DM (2009). "Scoring systems in acne vulgaris". Indian J Dermatol Venereol Leprol. 75 (3): 323–6. doi:10.4103/0378-6323.51258. PMID 19439902.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  2. ^ "Acne Vulgaris : Article by Julie C Harper". eMedicine. 6 August 2009. Retrieved 21 December 2009.
  3. ^ James WD (2005). "Clinical practice. Acne". N Engl J Med. 352 (14): 1463–72. doi:10.1056/NEJMcp033487. ISSN 0028-4793. PMID 15814882. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ Arndt, Hsu, Kenneth, Jeffrey (2007). Manual of dermatologic therapeutics. Lippincott Williams & Wilkins. ISBN 0-7817-6058-5.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. ^ a b Anderson, Laurence. 2006. Looking Good, the Australian guide to skin care, cosmetic medicine and cosmetic surgery. AMPCo. Sydney. ISBN 0-85557-044-X.
  6. ^ Thiboutot, Diane M.; Strauss, John S. (2003). "Diseases of the sebaceous glands". In Burns, Tony; Breathnach, Stephen; Cox, Neil; Griffiths, Christopher (ed.). Fitzpatrick's dermatology in general medicine (6th ed.). New York: McGraw-Hill. pp. 672–87. ISBN 0-07-138076-0.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. ^ Boil Drawing Salve, lovetoknow.com
  8. ^ a b Boils (Skin Abscesses), medicinenet.com
  9. ^ a b Goodman G (2006). "Acne and acne scarring - the case for active and early intervention" (PDF). Aust Fam Physician. 35 (7): 503–4. ISSN 0300-8495. PMID 16820822. {{cite journal}}: Unknown parameter |month= ignored (help)
  10. ^ Purvis D, Robinson E, Merry S, Watson P (2006). "Acne, anxiety, depression and suicide in teenagers: a cross-sectional survey of New Zealand secondary school students". J Paediatr Child Health. 42 (12): 793–6. doi:10.1111/j.1440-1754.2006.00979.x. ISSN 1034-4810. PMID 17096715. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
    One study has estimated the incidence of suicidal ideation in patients with acne as 7.1%:
    * Picardi A, Mazzotti E, Pasquini P (2006). "Prevalence and correlates of suicidal ideation among patients with skin disease". J Am Acad Dermatol. 54 (3): 420–6. doi:10.1016/j.jaad.2005.11.1103. ISSN 0190-9622. PMID 16488292. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  11. ^ ἀκμή, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  12. ^ "acne" at Dorland's Medical Dictionary
  13. ^ "acne vulgaris" at Dorland's Medical Dictionary
  14. ^ "acne rosacea" at Dorland's Medical Dictionary
  15. ^ "Acne Scars". www.acne-lasertreatment.net. Retrieved 9 September 2010.
  16. ^ Simpson, Nicholas B.; Cunliffe, William J. (2004). "Disorders of the sebaceous glands". In Burns, Tony; Breathnach, Stephen; Cox, Neil; Griffiths, Christopher (ed.). Rook's textbook of dermatology (7th ed.). Malden, Mass.: Blackwell Science. pp. 43.1–75. ISBN 0-632-06429-3.{{cite book}}: CS1 maint: multiple names: authors list (link)
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  19. ^ F. Ballangera, P. Baudrya, J.M. N'Guyenb, A. Khammaria, B. Dréno Heredity: A Prognostic Factor for Acne 5/2/2005
  20. ^ Chiu Annie, Chon Susan Y., Kimball Alexa B. (2003). "The Response of Skin Disease to Stress: Changes in the Severity of Acne Vulgaris as Affected by Examination Stress". Archives of Dermatology. 139 (7): 7. doi:10.1001/archderm.139.7.897. PMID 12873885. {{cite journal}}: More than one of |pages= and |page= specified (help)CS1 maint: multiple names: authors list (link)
  21. ^ National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health (January 2006). "Questions and Answers about Acne" [1], p. 5.
  22. ^ Yosipovitch G, Tang M, Dawn AG; et al. (2007). "Study of psychological stress, sebum production and acne vulgaris in adolescents". Acta Derm. Venereol. 87 (2): 135–9. doi:10.2340/00015555-0231. PMID 17340019. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  23. ^ USA. "Acne is Not Associated with Yet-Uncultured Bacteria". Ncbi.nlm.nih.gov. Retrieved 26 August 2012.
  24. ^ USA. "Population Genetic Analysis of Propionibacterium acnes Identifies a Subpopulation and Epidemic Clones Associated with Acne". Ncbi.nlm.nih.gov. Retrieved 26 August 2012.
  25. ^ "National Guideline Clearinghouse". Guideline.gov. 11/12/2007. {{cite web}}: Check date values in: |date= (help)
  26. ^ a b c Ferdowsian HR, Levin S (2010). "Does diet really affect acne?". Skin Therapy Lett. 15 (3): 1–2, 5. PMID 20361171. {{cite journal}}: Unknown parameter |month= ignored (help)
  27. ^ Smith RN, Mann NJ, Braue A, Mäkeläinen H, Varigos GA. (2007). "The effect of a high-protein, low glycemic-load diet versus a conventional, high glycemic-load diet on biochemical parameters associated with acne vulgaris: a randomized, investigator-masked, controlled trial". Journal of the American Academy of Dermatology. 57 (2): 247–56. PMID 17448569. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  28. ^ BC, Melnik. "Role of insulin, insulin-like growth factor-1, hyperglycaemic food and milk consumption in the pathogenesis of acne vulgaris.", Exp Dermatol, October 10, 2009, accessed August 07, 2011.
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