Dandruff occurs when the scalp sheds small bits of dry skin. You might spot these flakes in your hair or on your shoulders. Dandruff may make your scalp itchy, too.

It’s a common problem, but dandruff isn’t as simple as it seems. Dandruff can be tricky to define because it overlaps with seborrheic dermatitis (a chronic form of eczema) and other skin conditions that lead to a scaly scalp. Here’s what you need to know.

Telltale patches of white flakes on the scalp, made up of dead skin, that come loose in your hair are the clearest sign of dandruff. Other signs include the following:

• At times, the scalp can be itchy.

• Greasy or dry scales may develop on the scalp.

• A person with severe dandruff might notice yellowish to reddish scaly raised bumps along the hairline.

Dandruff can happen for a number of reasons.

Seborrheic Dermatitis

If you have particularly severe dandruff, it’s likely to be a mild case of seborrheic dermatitis (SD), according to the American Osteopathic College of Dermatology.

SD is a chronic form of eczema that affects areas of the body that secrete the most sebum, or oil, notes the National Eczema Association.People with oily skin are often more prone to dandruff. The reason: A yeast called Malassezia globosa feeds on oils on the scalp. Some people’s bodies perceive this breakdown of oil as an irritant, so the scalp reacts by upping the speed at which skin cells renew. This can lead to dandruff, notes Amy McMichael, MD, a professor of dermatology and the chair of the department of dermatology at Wake Forest School of Medicine in Winston-Salem, North Carolina. For those without dandruff, it takes a whole month for new skin cells on the scalp to mature, die, and shed. But for those with dandruff, this process occurs in a mere two to seven days.Still, it's important to note that even though M. globosa may be the main risk factor for dandruff, researchers have not yet established a causal relationship.

Contact Dermatitis

Contact dermatitis is skin irritation that occurs due to either an allergen or an irritant, resulting in an itchy, possibly painful rash. And in the case of dandruff, that reaction is on the scalp. According to the American Academy of Dermatology Association, this generally occurs because of hair-care products or dyes.

Dry Skin 

If cold winter air dries out your skin all over, including your scalp, then dry skin may be the cause of your dandruff. When dry skin causes dandruff, the flakes are usually smaller and less oily than the flakes caused by SD. In addition, cold and dry climates can worsen SD.

Almost anyone can have dandruff, but the following factors can make you more susceptible.

Shampooing Habits

“For those who are already at risk for dandruff, washing infrequently can worsen the condition,” says Dr. McMichael. Taking extended breaks can lead to a buildup of oil that can lead to dandruff.

Age

Dandruff is most common during infancy and middle age, according to a research review.

Sex 

Androgen hormones, such as testosterone, stimulate activity in the sebaceous glands. More oil means an increased chance of an inflammatory reaction and dandruff. Dandruff occurs more often in men than women.

Weakened Immune System

SD is more prevalent in individuals who’ve undergone an organ transplant and those with HIV or AIDS, hepatitis C, or alcoholic pancreatitis. For example, 30 percent to 83 percent of those with HIV report SD.

Neurologic and Psychiatric Conditions

Parkinson's disease, Alzheimer's disease, epilepsy, traumatic brain injury, and spinal cord injury are among the conditions that elevate a person's risk of SD, including dandruff. Those with Parkinson's disease, for example, have an impaired autonomic nervous system that helps to control factors like oil gland secretions, which can drive overproduction that leads to dandruff, according to the American Parkinson’s Disease Association.

History of Other Skin Disorders

Eczema, rosacea, psoriasis, or acne can trigger or worsen seborrheic dermatitis.

Oily Skin

If you have naturally oily skin, you’re at an elevated risk for seborrheic dermatitis.

Oiling Your Scalp

“Certain oils that people apply to the scalp can cover the scale but worsen the flaking and itching response,” notes McMichael.

A dermatologist can usually diagnose dandruff simply by looking at your scalp. If your dandruff does not respond to treatment, your healthcare provider may choose to perform a skin biopsy to rule out other possible issues, notes Cleveland Clinic.

Dandruff due to seborrheic dermatitis is a chronic condition that warrants repeated or long-term treatment. As for dandruff that arises from contact dermatitis, dry skin, or shampooing habits, a change of habits should clear up flakes fairly quickly.

Dandruff is an often chronic but treatable condition.

Gentle Over-the-Counter Shampoo

To reduce oil and skin cell buildup, wash your hair daily with a gentle shampoo, lightly massaging the scalp to loosen flakes, per Mayo Clinic. (See the section below for expert advice on the frequency of hair washing for Black women with dandruff.)

OTC Dandruff Shampoo

If gentle shampoo is not helping, try an over-the-counter (OTC) dandruff shampoo. It’s best to alternate between two or three of these shampoos, notes the American Osteopathic College of Dermatology. People with mild to moderate dandruff should look for dandruff shampoos that contain the following active ingredients.

• Selenium sulfide This antifungal slows the death of skin cells. This active ingredient can be found in Head & Shoulders Clinical Strength and Selsun Blue, among other shampoos.

• Pyrithione zinc This antibacterial and antifungal combo is in Head & Shoulders, DermaZinc, and Jason Dandruff Relief 2 in 1.

• Salicylic acid Neutrogena T/Sal and Baker's P&S both rely on salicylic acid to slough away flakes and promote healthier skin.

• Ketoconazole Nizoral A-D is a treatment that contains the antifungal ketoconazole. It is available both OTC and with a prescription. Manufacturers can also formulate ketoconazole as a shampoo, gel, or mousse.

• Tar Tar-based shampoos, like Neutrogena T/Gel, act as both an antibiotic and antifungal. But if you have blond, white, or gray hair, a tar shampoo can cause discoloration. This treatment can also make the scalp extra sensitive to sunlight.

Prescription Dandruff Treatment 

If regular and proper use of OTC shampoo for several weeks does not alleviate dandruff, ask your dermatologist if you’d benefit from a prescription-strength antifungal shampoo like Loprox or Nizoral, or a topical corticosteroid lotion, such as Capex or Synalar (fluocinolone topical), Luxiq (betamethasone topical), or Clobex (clobetasol topical). An alternative to corticosteroids for dandruff treatment is a class of drugs called calcineurin inhibitors. These, like Protopic (tacrolimus topical) and Elidel (pimecrolimus topical), work by suppressing the immune response, according to Harvard Health.The U.S. Food and Drug Administration also approved a plaque psoriasis treatment called roflumilast (Zoryve) as safe and effective for people who live with seborrheic dermatitis. You can apply it once daily, and its clinical trials found that Zoryve can significantly clear disease symptoms and reduce itch.

Alternative and Complementary Therapies

Tea tree oil Tea tree oil may act as an antiseptic, antibiotic, and antifungal agent. Shampoos or topicals that contain 5 percent tea tree oil appear to be a safe and effective treatment for dandruff, according to a small randomized study.Healthy fats Increasing your intake of omega-3 fatty acids, like those found in salmon, tuna, and mackerel, will help regulate oil production on the skin, notes Cedars-Sinai.

Additional Approaches

Get some sun. Brief bouts of sunshine can help reduce yeast production on the scalp. But if you are also using a tar-based dandruff treatment, avoid direct sun exposure, as your scalp is especially sensitive to sunlight.Cut back on hair products. Styling gels, sprays, pomades, and more can build up on the hair and scalp, increasing oiliness and dandruff.

Prevention of Dandruff

“You can prevent the signs and symptoms of dandruff, but there is no cure for dandruff,” says McMichael. If you’ve got an especially oily scalp, daily shampooing with a gentle cleanser, coupled with a light scalp massage, may help prevent dandruff in certain cases. If you're using an OTC dandruff shampoo, talk to your dermatologist about how often to use it for maintenance and prevention. Finally, increased omega-3 intake, brief exposure to sun, and fewer hair products can help prevent dandruff as well.

One review found that seborrheic dermatitis is among the five most common diagnoses that Black people receive and that it’s particularly common among Black women. Unfortunately, Black women also tend to face some common dandruff-treatment barriers. “Because many Black women do not wash their hair frequently through the week, this can make dandruff worse and treatment challenging,” notes McMichael, who recommends Black women aim to wash at least every two weeks, but once weekly is best. Another barrier: Medicated shampoos tend to be great for the scalp but not for healthy Black hair, because of hair shaft dryness. “That means that using these shampoos on the scalp alone, not the whole head of hair, is often best,” says McMichael.

Around 5 percent of the global population has seborrheic dermatitis, but dandruff might occur in closer to half of all people.

“Sometimes what you think is dandruff is simply product debris, like hair gel or hair spray,” says McMichael. Other times, it may be one of these conditions.

Cradle cap Technically, seborrheic dermatitis and cradle cap and dandruff are all the same thing. Cradle cap occurs in infants between two weeks and 12 months old. They develop greasy, scaly, or crusty red or yellow patches on the scalp. The flaky rash can also appear on the face, diaper area, and other areas of the body.Scalp psoriasis About 50 percent of people who have plaque psoriasis experience a flare-up on the scalp at some point. On the scalp, you may have reddish patches, dandruff-like flaking, silvery-white scale, and dryness. Scalp psoriasis is often itchy, with the itch ranging from mild to intense, notes the American Academy of Dermatology Association.Tinea capitis This highly contagious fungal infection is also called ringworm of the scalp and hair shafts. Symptoms may include itchy, scaly, and bald patches on the head. Tinea capitis is most common in toddlers and school-age children, per the Mayo Clinic.

Skin of Color Society

This professional dermatologic organization is dedicated to promoting awareness of (and excellence within) the dermatological care of skin of color. SCS offers a Find a Doctor database to help those of Asian, Hispanic or Latino, African, Native American, and Pacific Island descent find local dermatologists who are especially knowledgeable about their skin concerns. Whether you’re struggling to find a dermatologist who can help treat persistent dandruff in Black hair or you’ve got another skin-related issue, SCS’s Find a Doctor database can help.

American Academy of Dermatology

The AAD is the largest dermatology group in the United States, and its website is full of resources, tips, and more. Curious how to ease your itchy skin? Check out their Everyday Care section. Not sure how to combat your child’s dandruff? Go to the areas dedicated to Parents and Kids.

• Dandruff symptoms may include small pieces of dry skin on your scalp, in your hair, and on your shoulders. You may also have an itchy scalp, or yellowish to reddish scaly raised bumps in more severe cases.

• If you have excessive dandruff or the symptoms are more severe, you may have a skin condition such as seborrheic dermatitis. Age, sex, ethnicity, and neurologic conditions may also be factors for those who have lots of dandruff.

• Dandruff shampoo, which often contains active ingredients like selenium sulfide, pyrithione zinc, salicylic acid, is available over the counter or by prescription. Shampoos containing tea tree oil may also help.

• To help prevent dandruff, increase your intake of omega-3s and try more sunlight exposure.