Brown spots on the palms can result from dozens of different causes, ranging from harmless staining to infections, nutritional deficiencies, medication side effects, and occasionally serious systemic disease. What makes palmar spots distinctive is that the palms are not like other skin. They are thicker, largely hairless, and have a different relationship with pigment-producing cells than the rest of your body. Because of that, a brown spot that shows up specifically on a palm often signals something different from the freckle on your forearm. Understanding the most common and most important causes helps you figure out when a spot is worth ignoring and when it deserves a doctor’s attention.
Why Palms Are Different From Other Skin
The skin on your palms and soles is structurally unlike the skin covering the rest of your body. It is much thicker, built for gripping and weight-bearing, and it lacks hair follicles and the oil glands that come with them. Pigmentation behaves differently here too. Research using single-cell analysis of palm skin found that while melanocyte-like cells are present in the palm’s deeper layers, many of them lack the genes that actually produce pigment.
In practical terms, this means your palms are naturally lighter than most of the rest of your skin, regardless of your overall skin tone. When brown discoloration does appear on the palms, it stands out more and is less likely to be explained by routine sun exposure. That is why clinicians pay close attention to palmar spots: the usual explanation for dark spots elsewhere on the body (cumulative UV damage) does not apply as readily to palms, so the differential diagnosis shifts toward other causes.
Fungal Infection: Tinea Nigra
One of the more distinctive causes of a brown or dark patch on the palm is tinea nigra, a superficial fungal infection caused by the melanized fungus Hortaea werneckii. It produces irregular, flat, dark patches that look almost painted on, and it overwhelmingly favors the palms. In a series of 22 cases from Mexico, 19 involved the palms and only three affected the soles of the feet.1PubMed Central. Tinea nigra by Hortaea werneckii, a report of 22 cases from Mexico A systematic review of the condition describes it as characterized by irregular dark patches typically on the palms.2PubMed Central. Systematic Review of Tinea Nigra: A Clinical Approach
Tinea nigra is painless and does not itch, which is part of why it gets underreported and sometimes misdiagnosed. It is most common in tropical and subtropical regions, though cases appear worldwide. A case report from a rural Ethiopian hospital described an older man with dark plaques on both palms whose diagnosis was confirmed by finding brownish fungal filaments under a microscope after a simple skin scraping.3PubMed Central. Tinea nigra palmaris: a clinical case in a rural Ethiopian hospital This is important because the patches can be mistaken for melanoma, leading to unnecessary biopsies. If you have a painless, flat, dark patch on your palm that is not raised and does not change rapidly, tinea nigra is one of the things a dermatologist should consider before jumping to more alarming conclusions. The infection responds well to topical antifungal treatment.
Postinflammatory Hyperpigmentation
Any injury or inflammation to the skin can leave behind a brown mark as it heals. This is called postinflammatory hyperpigmentation, and it happens because inflammation revs up the melanocytes in the affected area, causing them to dump extra pigment into the surrounding skin cells. If the damage goes deeper and disrupts the base layer of the skin, pigment leaks down into the dermis, where it gets trapped by immune cells and can persist for months or even years.4DermNet. Postinflammatory hyperpigmentation
On the palms, this can follow burns, friction blisters, contact dermatitis, or eczema flares. People with darker skin tones are more prone to postinflammatory hyperpigmentation in general because their melanocytes are more reactive. If you had a blister or rash on your palm and noticed a brown spot after it resolved, this is the most likely explanation. The marks usually fade on their own, though deeper (dermal) pigment deposits take longer and sometimes need treatment to clear.
Vitamin B12 Deficiency
A surprisingly underrecognized cause of brown spots on the hands, especially the palms, is vitamin B12 deficiency. Most people associate low B12 with fatigue or nerve tingling, but skin darkening can be one of the earliest signs and sometimes the only sign initially. A case report described a 35-year-old woman who developed progressive, non-scaly dark patches on her palms, soles, and knuckles over a year as the primary manifestation of B12 deficiency.5International Journal of Scientific Reports. A hidden deficiency unveiled by hyperpigmentation: a case report of vitamin B12 deficiency Another report described symmetric pigmentation on the backs of the hands and palms in a long-term vegetarian, highlighting that this skin change is an overlooked early clue.6PubMed Central. Skin Hyperpigmentation: An Under-Recognized Dermatological Clue to Vitamin B12 Deficiency
The mechanism is not completely understood, but B12 plays a role in melanin synthesis pathways, and a deficiency appears to cause melanocytes to overproduce pigment. Strict vegetarians, vegans, people with absorption problems like pernicious anemia, and those who have had gastric surgery are at higher risk. The hyperpigmentation typically reverses with B12 supplementation, though it can take weeks to months. If you develop unexplained darkening on your palms and knuckles without any history of injury or sun exposure, it is worth having your B12 level checked with a simple blood test.7PubMed Central. Hyperpigmentation as a Primary Symptom of Vitamin B12 Deficiency: A Case Report
Addison’s Disease and Hormonal Causes
Addison’s disease, a condition in which the adrenal glands do not produce enough cortisol, causes a very characteristic pattern of skin darkening. When the adrenal glands fail, the pituitary gland compensates by producing more of a hormone called ACTH. That same hormone stimulates melanocytes throughout the body, leading to generalized hyperpigmentation that affects not only sun-exposed skin but also the palms and even the gums.8Patient Care. Addison’s Disease
What distinguishes Addisonian hyperpigmentation from most other causes is its distribution. It darkens the creases of the palms, the inside of the mouth, old scars, and areas of friction. If you notice brown patches in your palm creases along with fatigue, weight loss, low blood pressure, or salt cravings, this combination warrants urgent medical evaluation. Addison’s disease is rare but can be life-threatening if undiagnosed, and the skin changes are often the clue that leads to the diagnosis.
Syphilis
Secondary syphilis is one of the classic infections known for producing reddish-brown spots on the palms and soles, a distribution unusual enough that it has been considered a clinical hallmark for centuries. A case report described a young man with reddish-brown patches on his face, palms, and soles along with genital lesions, representing a characteristic presentation of secondary syphilis reinfection.9Indonesian Journal of Case Reports. Secondary Syphilis Reinfection with Suspected Asymptomatic Neurosyphilis
The rash of secondary syphilis typically appears weeks to months after the initial painless sore has healed, so many people do not connect the two. The palmar lesions tend to be round, copper-colored, non-itchy macules or slightly scaly patches. They can be subtle enough to be mistaken for eczema or an allergic reaction. Because syphilis rates have risen significantly in recent years, clinicians are increasingly alert to this presentation. If you develop unexplained brown or reddish-brown spots on both palms, especially with any history of sexual exposure, getting tested is straightforward and the infection is curable with antibiotics.
Drug-Induced Discoloration
Certain medications can cause brown spots on the palms as a side effect. The chemotherapy drug capecitabine is one of the better-documented offenders. It frequently causes hand-foot syndrome, a painful redness and peeling of the palms and soles, and it can also cause marked hyperpigmentation of the hands, feet, face, and mouth.10PubMed Central. Hyperpigmentation with Capecitabine: Part of Hand-Foot Syndrome or a Separate Entity? The darkening was initially assumed to be part of hand-foot syndrome, but case evidence suggests it can occur independently as a separate reaction. One report described an 82-year-old man who developed progressive hyperpigmentation of his hands, feet, face, and tongue after starting capecitabine for colon cancer without any of the painful peeling associated with hand-foot syndrome.11SKIN: The Journal of Cutaneous Medicine. Why is My Skin Turning Black? A Rare Side Effect of Capecitabine
Beyond chemotherapy, other medications can leave marks on the palms through a different mechanism called fixed drug eruption. These are circular, dusky or brownish patches that appear in the same spot every time you take a particular drug. They are most commonly associated with certain antibiotics, pain relievers, and anti-seizure medications. After the active reaction subsides, a persistent brown patch often remains. If a brown spot on your palm keeps reappearing in the same location and you can link it to taking a specific medication, fixed drug eruption is a strong possibility.
Arsenic Exposure
Chronic arsenic exposure, whether from contaminated drinking water, occupational contact, or certain traditional remedies, produces a distinctive pattern of skin changes that includes spotted pigmentation on the palms and soles along with thickening of the skin. Research in Taiwan linked high-arsenic water exposure to altered skin pigmentation, thickening of the palms and soles, and increased cancer risk.12IntechOpen. Exploring the Interplay between Arsenic and Cutaneous Physiology, Pathology, and Regeneration A study in northwestern Iran found that skin pigmentation changes were significantly more common in people exposed to arsenic-contaminated water compared to unexposed controls.13PubMed Central. Arsenic exposure, dermatological lesions, hypertension, and chromosomal abnormalities among people in a rural community of northwest Iran
The pigmentation pattern from arsenic is sometimes described as “raindrop” hyperpigmentation: scattered small dark spots against a slightly lighter background, often on the trunk and extremities including the palms. In many parts of the world, groundwater contamination with arsenic remains a public health concern. If you live in an area with known arsenic issues or have occupational exposure, skin changes on the palms should prompt testing.
Genetic Syndromes With Palmar Spots
A few inherited and acquired syndromes specifically produce pigmented spots on the palms and around the mouth. Peutz-Jeghers syndrome is a genetic condition characterized by dark freckle-like spots on the lips, around the eyes and nostrils, on the buccal mucosa inside the cheeks, and on the fingers, palms, and soles. In a study of affected families, the index case had melanotic spots on the palms, soles, and face in addition to the oral mucosa.14PubMed Central. Peutz–Jeghers Syndrome: Lessons to be Learned in the Clinical Diagnosis The syndrome also involves polyps in the gastrointestinal tract and carries an increased risk of certain cancers, making recognition of the skin signs important for early diagnosis.
Laugier-Hunziker syndrome is a separate, acquired, and benign condition that also produces pigmented spots on the lips, inside the mouth, and on the fingertips and palms. It is often confused with Peutz-Jeghers syndrome, but it does not carry the same cancer risks or gastrointestinal complications.15PubMed Central. Laugier-hunziker syndrome: a rare cause of oral and acral pigmentation Distinguishing between the two matters considerably: one requires lifelong cancer surveillance while the other is purely cosmetic. If you have brown spots on both your palms and your lips or inside your mouth, bring it up with your doctor, because the combination narrows the diagnostic possibilities and may warrant further evaluation.
Janeway Lesions and Vascular Causes
Small, painless brown or reddish-brown spots on the palms can occasionally be a sign of infective endocarditis, a serious infection of the heart valves. These spots are known as Janeway lesions, and they result from tiny clumps of infected material breaking off the heart valves and lodging in small blood vessels of the hands and feet, forming micro-abscesses in the skin.16PubMed Central. Image of the month: ‘Diagnostic hands’: Janeway lesions They are considered a hallmark of the condition, and while they are not common, spotting them can be lifesaving because endocarditis requires urgent treatment.
Janeway lesions are flat, non-tender, and can look deceptively innocent, like simple brown spots. They tend to appear alongside systemic symptoms like fever, fatigue, and new heart murmur. If you have unexplained brown or dusky spots on your palms and you have been feeling unwell with fevers or chills, particularly if you have a known heart valve problem or have had recent dental or surgical procedures, seek medical attention promptly.
Phytophotodermatitis and External Staining
Not every brown spot on the palm comes from inside the body. Phytophotodermatitis is a skin reaction that occurs when certain plant compounds called furocoumarins come into contact with your skin and are then activated by sunlight. Psoralen, found in limes, lemons, celery, parsnips, figs, and several other plants, is the most common culprit. The reaction produces redness followed by dark brown staining that can persist for weeks or months, and the palms are a prime location because hands are what handle food and plants.
The classic scenario involves squeezing limes outdoors on a sunny day, producing brown streaks or blotches on the palms and fingers a day or two later. Bartenders and cooks are commonly affected. The brown marks are simply residual pigmentation from the skin’s inflammatory reaction and are not dangerous, but they can be cosmetically bothersome and take a while to fade. If your brown spots appeared shortly after handling citrus or certain herbs in sunlight, this is a likely explanation.
Simple exogenous staining is even more mundane. Handling certain dyes, chemicals, spices like turmeric, walnut hulls, henna, or certain cleaning products can leave brown marks on the palms that look like pigmented lesions but are just surface deposits. These usually wash off with time or with alcohol-based solvents, and a dermatologist can distinguish them from true pigment changes during examination.
Solar Lentigines and Sun Exposure
Solar lentigines, commonly called age spots or sun spots, are the most familiar type of brown spot on the skin. They result from years of cumulative UV exposure and appear most often on the backs of the hands, face, neck, and arms.17Wiley Online Library. Treatment of Solar Lentigines: A Systematic Review of Clinical Trials The palms, however, are an unusual location for solar lentigines because the thick stratum corneum of palmar skin and the way hands are naturally positioned mean the palms get far less UV exposure than the backs of the hands. If you have a brown spot on the back of your hand, sun damage is the most likely explanation. A brown spot on the palm is a different story and deserves a broader differential.
That said, palms are not completely immune. People who work outdoors with their palms regularly facing upward, or who use tanning beds, can develop sun-related pigmentation on the palms in rare cases. But as a general rule, when a brown spot appears specifically on the palm rather than the dorsal hand, looking beyond UV damage is the right approach.
When to Be Concerned
Most brown spots on the palms are benign, but certain features warrant a prompt visit to a dermatologist. Any spot that is asymmetric, has irregular borders, shows multiple colors within it, is larger than about six millimeters, or is actively changing in size, shape, or color should be evaluated to rule out acral melanoma. This is a type of melanoma that occurs specifically on the palms, soles, and under the nails, and it is proportionally more common in people with darker skin tones who are otherwise at lower risk for other types of melanoma. Acral melanoma is often diagnosed late because both patients and clinicians do not think to look at the palms for skin cancer.
Brown spots accompanied by systemic symptoms also deserve attention. Spots paired with fatigue and low blood pressure point toward Addison’s disease. Spots with fever point toward endocarditis or syphilis. Spots with numbness or tingling suggest B12 deficiency. The palms are in some ways a diagnostic window, and a brown spot there tells a broader story about what might be happening throughout the body. A simple photograph taken over time can help you and your clinician track whether a spot is changing, which is one of the most useful pieces of information in deciding whether further workup is needed.