Hyperpigmentation is darkening of the skin relative to normal pigmentation (colour).
Please note that while ‘pigmentation’ is the most commonly used term, the correct medical term is ‘hyperpigmentation.’
What is the mechanism of pigmentation?
Hyperpigmentation of the skin is determined by the relative deposition of melanin. There are two types of melanin:
- Eumelanin: black-brown
- Pheomelanin: yellow-red
Melanin is produced by a specialised cell called a melanocyte which lives in the top layer (epidermis) of the skin. Melanocytes produce melanin and transfers the pigment to the surrounding skin cells (keratinocytes). Darker skin has more melanin than lighter skjn, furthermore, skin colour can also be influenced by blood flow, carotene, lycopene, and collagen.2Speeckaert R, Van Gele M, Speeckaert MM, Lambert J, van Geel N. The biology of hyperpigmentation syndromes. Pigment Cell Melanoma Res. 2014;27(4):512-524. doi:10.1111/pcmr.12235,3Ranu H, Thng S, Goh BK, Burger A, Goh CL. Periorbital hyperpigmentation in Asians: an epidemiologic study and a proposed classification. Dermatol Surg. 2011;37(9):1297-1303. doi:10.1111/j.1524-4725.2011.02065.x
Hyperpigmentation most commonly results from increased production and deposition of melanin. Other pigments, such as hemosiderin (a form of iron), can leech out of the blood into the skin, resulting in discolouration.
What are the common causes of pigmentation?
While there are numerous causes of hyperpigmentation, many of these are very rare. We have listed the most common causes of hyperpigmentation below.
Freckles
Freckles or ephelides commonly develop during childhood in the sun-exposed areas of people with fair skin. They are typically small (2-4 mm), and the intensity can vary with seasonal sun exposure.
Effective treatments are:
- Intense pulsed light (IPL), particularly for large areas
- Q-switched Alexandrite lasers
- Picosecond lasers
Lentigenes
Often referred to as sun spots, age spots, or liver spots; solar lentigines are very common and occur in chronically sun-exposed areas of adult skin. They are larger than freckles, ranging in size from 5 to 20 mm. They can develop after new episodes of sunburn.
The treatments that have been shown to be effective are:
- Intense pulsed light (IPL) which are particularly useful for treating large areas
- Q-switched Nd:YAG
- Picosecond lasers
- Fractionated lasers
Melasma pigmentation
Melasma typically presents as a mask-like hyperpigmentation on the face. It is most common in women with darker skin types.
We discuss melasma in more detail on our Definitive Guide to Melasma page.
Poikiloderma of Civatte
Poikiloderma is a chronic, progressive condition that manifests with atrophy of the skin, telangiectasia, and a mottled pigmentation pattern. It typically involves the lateral cheeks, neck, and décolletage. Chronic UV light exposure is usually the cause, and it generally presents after the age of 40. Poikiloderma mostly affects women with fair skin.4Cestari TF, Dantas LP, Boza JC. Acquired hyperpigmentations. An Bras Dermatol. 2014;89(1):11-25. doi:10.1590/abd1806-4841.20142353
The treatments that have been shown to be effective are:
- Intense pulsed light (IPL) which are particularly useful for treating large areas
- Q-switched Nd:YAG
- Picosecond lasers
- Fractionated lasers
Dermatosis papulosa nigra (DPN)
Dermatosis papulosa nigra is a very common condition that presents with multiple small, dark, raised lesions that are approximately 1 to 5 mm. They most commonly develop on the face, neck, and upper back. It occurs in around 50% of those with darkly pigmented skin.5Veraitch O, Rickaby W, Robson A, Higgins E, Mellerio JE. Early-onset dermatosis papulosa nigra. Br J Dermatol. 2016;174(5):1148-1150. doi:10.1111/bjd.14324,6Babapour R, Leach J, Levy H. Dermatosis papulosa nigra in a young child. Pediatr Dermatol. 1993;10(4):356-358. doi:10.1111/j.1525-1470.1993.tb00398.x
The cause of DPN is unknown, however, there appears to be a genetic predisposition. DPN is not harmful, but it causes cosmetic concerns for many people. There are multiple treatment options, including electrodessication, cryotherapy, and lasers.
Maturational pigmentation
This is a progressive darkening of facial skin, primarily in sun-exposed areas of older people. Maturational hyperpigmentation mostly affects the face, hands, and feet. The exact cause is unknown.
It is normally treated with sun protection and skin-lightening creams.
Periorbital pigmentation
Periorbital pigmentation (more commonly known as ‘dark circles under the eyes‘) is a very common occurrence. It is generally symmetrical and affects both men and women, although it tends to be more common in people with darker skin.7Sarkar R. Idiopathic cutaneous hyperchromia at the orbital region or periorbital hyperpigmentation. J Cutan Aesthet Surg. 2012;5(3):183-184. PMCID: PMC3483574
There are multiple contributing factors for periorbital hyperpigmentation, including sun exposure, genetics, oedema & vascularity, and thin & translucent lower eyelid skin.
Unfortunately, there is no definitive cure for this, however, recommendations suggest targeting treatment towards the most likely cause of the pigmentation. Examples include:
- Postinflammatory hyperpigmentation: hydroquinone cream
- Fillers for significant atrophy
- Chemical peels and lasers have also been used
Acanthosis nigricans
Acanthosis nigricans is a very common condition that manifests as darkened skin with a velvety thickening that occurs in areas of skin folds (intertriginous areas). These areas include the neck, axillae (armpit), and groin.
Unlike other causes of hyperpigmentation, the darkening is caused by hyperkeratosis (thickening of the skin), not increased melanin deposition.8Murphy-Chutorian B, Han G, Cohen SR. Dermatologic manifestations of diabetes mellitus: a review. Endocrinol Metab Clin North Am. 2013;42(4):869-898. doi:10.1016/j.ecl.2013.07.004 Acanthosis nigricans has a very strong association with insulin resistance syndromes. Because of this, it occurs in about 40% of those with Type 2 Diabetes Mellitus and about 51% of those with obesity.9Kong AS, Williams RL, Smith M, et al. Acanthosis nigricans and diabetes risk factors: prevalence in young persons seen in southwestern US primary care practices. Ann Fam Med. 2007;5(3):202-208. doi:10.1370/afm.678
While acanthosis is benign, it is a cosmetic concern for many people.
Treatment of Acanthosis Causes
The first line of treatment is to address the underlying cause:
- Weight loss has been shown to improve acanthosis nigricans.10Kuroki R, Sadamoto Y, Imamura M, et al. Acanthosis nigricans with severe obesity, insulin resistance and hypothyroidism: improvement by diet control. Dermatology. 1999;198(2):164-166. doi:10.1159/000018096,11Pasquali R, Antenucci D, Casimirri F, et al. Clinical and hormonal characteristics of obese amenorrheic hyperandrogenic women before and after weight loss. J Clin Endocrinol Metab. 1989;68(1):173-179. doi:10.1210/jcem-68-1-173,12Novotny R, Davis J, Butel J, et al. Effect of the Children’s Healthy Living Program on Young Child Overweight, Obesity, and Acanthosis Nigricans in the US-Affiliated Pacific Region: A Randomized Clinical Trial. JAMA Netw Open. 2018;1(6):e183896. Published 2018 Oct 5. doi:10.1001/jamanetworkopen.2018.3896
- Improved diabetes control also improves acanthosis nigricans.13Sett A, Pradhan S, Sancheti K, et al. Effectiveness and Safety of Metformin versus Canthex™ in Patients with Acanthosis Nigricans: A Randomized, Double-blind Controlled Trial. Indian J Dermatol. 2019;64(2):115-121. doi:10.4103/ijd.IJD_417_17,14Bellot-Rojas P, Posadas-Sanchez R, Caracas-Portilla N, et al. Comparison of metformin versus rosiglitazone in patients with Acanthosis nigricans: a pilot study. J Drugs Dermatol. 2006;5(9):884-889.,15Tankova T, Koev D, Dakovska L, Kirilov G. Therapeutic approach in insulin resistance with acanthosis nigricans. Int J Clin Pract. 2002;56(8):578-581.
- Other treatments are normally targeted at reducing the overproliferation of skin in areas of acanthosis nigricans. These treatments include topical and systemic retinoids. Some of these treatments can be very effective.16Hermanns-Lê T, Hermanns JF, Piérard GE. Juvenile acanthosis nigricans and insulin resistance. Pediatr Dermatol. 2002;19(1):12-14. doi:10.1046/j.1525-1470.2002.00013.xWalling HW, Messingham M, Myers LM, Mason CL, Strauss JS. Improvement of acanthosis nigricans on isotretinoin and metformin. J Drugs Dermatol. 2003;2(6):677-681.,17Swineford SL, Drucker CR. Palliative treatment of paraneoplastic acanthosis nigricans and oral florid papillomatosis with retinoids. J Drugs Dermatol. 2010;9(9):1151-1153.,18Katz RA. Treatment of acanthosis nigricans with oral isotretinoin. Arch Dermatol. 1980;116(1):110-111. doi:10.1001/archderm.1980.01640250112027,19Böhm M, Luger TA, Metze D. Treatment of mixed-type acanthosis nigricans with topical calcipotriol. Br J Dermatol. 1998;139(5):932-934. doi:10.1046/j.1365-2133.1998.02538.x,20Blobstein SH. Topical therapy with tretinoin and ammonium lactate for acanthosis nigricans associated with obesity. Cutis. 2003;71(1):33-34.,21Adigun CG, Pandya AG. Improvement of idiopathic acanthosis nigricans with a triple combination depigmenting cream. J Eur Acad Dermatol Venereol. 2009;23(4):486-487. doi:10.1111/j.1468-3083.2008.02931.x
Erythema ab igne
Erythema ab igne presents as a lace-like (reticular) pattern of hyperpigmentation that results from intense or repeated exposure to significant heat. Common causes are direct skin contact with hot-water bottles or heating pads for prolonged periods of time. Sometimes it occurs when leaning up against a heater.
Erythema ab igne will normally settle after removal of the heat source, although chronic pigmentation can persist long-term.22Mirgh SP, Shah VD, Sorabjee JS. Perils of Technology – Laptop Induced Erythema Ab Igne (Toasted Skin Syndrome) on Abdomen. Indian J Occup Environ Med. 2020;24(2):131-132. doi:10.4103/ijoem.IJOEM_12_19
Postinflammatory hyperpigmentation
Postinflammatory hyperpigmentation is caused by an inflammatory process in the skin as a result of inflammatory mediators that stimulate the melanocytes to release more melanin into the skin. Due to the architectural disruption that can occur during the inflammatory process, some of this melanin can deposit in the deeper layers of the skin such as the dermis.
Furthermore, macrophages that normally live in the dermis may enter the epidermis during inflammation, gobble up excess melanin, and then return to the dermis with this pigment. As a result, postinflammatory pigmentation can exist in both the superficial epidermis and deeper layers (such as the dermis). Of course, this variable depth has implications for the treatment of postinflammatory hyperpigmentation and success rates.23Epstein JH. Postinflammatory hyperpigmentation. Clin Dermatol. 1989;7(2):55-65. doi:10.1016/0738-081x(89)90057-6,24Callender VD, St Surin-Lord S, Davis EC, Maclin M. Postinflammatory hyperpigmentation: etiologic and therapeutic considerations. Am J Clin Dermatol. 2011;12(2):87-99. doi:10.2165/11536930-000000000-00000,25Hasan AT, Eaglstein W, Pardo RJ. Solar-induced postinflammatory hyperpigmentation after laser hair removal. Dermatol Surg. 1999;25(2):113-115. doi:10.1046/j.1524-4725.1999.08108.x,26Tomita Y, Maeda K, Tagami H. Mechanisms for hyperpigmentation in postinflammatory pigmentation, urticaria pigmentosa and sunburn. Dermatologica. 1989;179 Suppl 1:49-53. doi:10.1159/000248449,27Davis EC, Callender VD. Postinflammatory hyperpigmentation: a review of the epidemiology, clinical features, and treatment options in skin of color. J Clin Aesthet Dermatol. 2010;3(7):20-31. PMCID:PMC2921758,28Masu S, Seiji M. Pigmentary incontinence in fixed drug eruptions. Histologic and electron microscopic findings. J Am Acad Dermatol. 1983;8(4):525-532. doi:10.1016/s0190-9622(83)70060-5,29Vashi NA, Kundu RV. Facial hyperpigmentation: causes and treatment. Br J Dermatol. 2013;169 Suppl 3:41-56. doi:10.1111/bjd.12536
Numerous different insults to the skin can cause postinflammatory hyperpigmentation, including rashes, burns, traumatic injuries, acne, and eczema.
What are the treatments for pigmentation?
Treatment can be difficult, as many types recur due to the chronic and persistent nature of the underlying causes.
Sun protection
Despite the cause of hyperpigmentation, dermatologists will generally always recommend ultraviolet and visible light protection. This includes avoiding peak sunlight hours, wearing protective clothing, and high SPF sunscreens. Tinted sunscreen with a minimum concentration of 3% iron oxide is the most effective at protecting against visible light.30Geisler AN, Austin E, Nguyen J, Hamzavi I, Jagdeo J, Lim HW. Visible light. Part II: Photoprotection against visible and ultraviolet light. J Am Acad Dermatol. 2021;84(5):1233-1244. doi:10.1016/j.jaad.2020.11.074,31Lyons AB, Trullas C, Kohli I, Hamzavi IH, Lim HW. Photoprotection beyond ultraviolet radiation: A review of tinted sunscreens. J Am Acad Dermatol. 2021;84(5):1393-1397. doi:10.1016/j.jaad.2020.04.079
You can head over to the Skintel website to learn more about sunscreen and sun protection.
Laser treatments
Laser and intense pulsed light treatments can be very effective for many different types of hyperpigmented conditions. However, different devices will be used for different conditions, depending on their varying characteristics as well as benefits and potential side effects.
Other treatments
Please note this section may seem vague as we have avoided naming some specific medications. Regulators, particularly Medsafe don't allow us to write about the Off-Label Use of medications. However, these are permitted to be discussed during your consultation, so you are welcome to ask.
While there are several topical treatments to help with hyperpigmentation, these are mostly used in the context of melasma and are therefore discussed in more detail on our Definitive Guide to Melasma page.
Chemical peels are becoming more commonly used for the treatment of hyperpigmentation. Typical peeling agents include glycolic acid, salicylic acid, and trichloroacetic acid.