Dry scalp
Dry scalp may cause mild itching and small, dry flakes. Dry scalp is more common in the winter and may be caused by colder air and indoor heating. If you have dry scalp, you often have dry skin in other areas of the body. Dry scalp may also stem from hair care products or hair care processes such as hair drying with heat, coloring, or chemical straightening.
Treatment
Cleansing with a gentle shampoo for sensitive skin followed by a mild hair conditioner may be all that is needed. Avoid common chemical irritants found in certain hair care products which may cause the scalp to become dry and itchy. If gentle cleansing and conditioning does not resolve the issue, consider whether the underlying problem may actually be dandruff.
Sensitive scalp
Irritated scalp may result from sensitivities or allergies to certain hair care products or hair care processes and result in a red, itchy or scaly scalp.
Treatment
If you know what products or ingredients trigger your irritation, avoid them. Look for gentle hair care products free of common chemical irritants. Also, look for products labeled as ‘hypoallergenic’ or ‘fragrance-free’ as they tend to be less irritating to sensitive skin and scalp.
When to See a Doctor
If you cannot identify the cause of your irritation, consult with an allergist or dermatologist about your concerns. These physicians can help identify specific ingredients of concern and develop a plan to help avoid them.
Dandruff
Dandruff is a common condition that causes flaking of the skin on the scalp producing small, loose, gray or white flakes. These flakes are typically larger than what is seen with dry scalp. Scalp associated with dandruff is typically itchy, oily and scaly but not inflamed.
Dandruff forms when excess skin cells on the scalp die and fall off. A common yeast-like fungus (malassezia) that lives on the skin and scalps of most adults is associated with dandruff. For some people, it irritates the scalp and causes the formation of the excess skin cells. This fungus lives off skin oils which is why people with oily skin and scalp are more prone to dandruff.
Treatment
Daily cleansing with a gentle shampoo to reduce oiliness and skin cell build-up can help in removing loose flakes. For some people this may be sufficient, but it does not treat the cause of the dandruff. To treat dandruff, look for an over-the-counter (OTC) medicated dandruff shampoo.
Anti-dandruff shampoos that contain pyrithione zinc treat dandruff and are typically gentle enough for daily use. If you have dandruff and sensitive skin or scalp, look for an anti-dandruff shampoo free of common chemical irritants . There may be some trial and error in determining how frequently you need to use shampoos for dandruff. For the days you don’t use an anti-dandruff shampoo, alternate with a mild, fragrance-free shampoo and hair conditioner to help avoid further irritation. Because not all medicated products are the same, always follow product directions.
When to See a Doctor
If symptoms become unmanageable or there are signs of infection, contact a doctor or dermatologist who can prescribe prescription strength products to get your symptoms under control.
Seborrheic Dermatitis
Seborrheic dermatitis is an inflammatory skin condition associated with the oily areas of the body including the scalp, face, eyebrows, ears, eyelids, chest, armpits, groin, or under the breasts. Common symptoms include greasy, white to yellow, scaly or crusty patches and white to yellow, oily flakes on the scalp, hair, eyebrows, beard or mustache. The skin may become red, inflamed, and be accompanied by excessive itching. Seborrheic dermatitis, sometimes referred to as ‘seb derm’, is typically chronic and relapses and flare-ups are common.
As compared to dandruff, seborrheic dermatitis of the scalp causes more flaking, and the flakes tend to be larger with an oily, yellow appearance. Redness and Inflammation may be present and itching can be more intense. Although seborrheic dermatitis and dandruff are closely related, the key difference is in the severity of symptoms and where the symptoms occur. The term dandruff is used when the symptoms are mild and are confined to the scalp. Seborrheic dermatitis is typically reserved for more severe symptoms and/or the symptoms are present in other body areas. The underlying causes are the same, which is why some of the treatments for dandruff are also effective in combating seborrheic dermatitis.
As in dandruff, seborrheic dermatitis is caused when cells on the skin and/or scalp multiply in excess. These excess skin cells accumulate in patches and shed, forming flakes. A common yeast-like fungus (malassezia) that lives on the skin and scalps of most adults is associated with dandruff and seborrheic dermatitis. For some people, it irritates the skin and scalp and causes the formation of the excess skin cells. This fungus lives off skin oils which is why people with oily skin and scalp are more prone to dandruff and seborrheic dermatitis.
Certain underlying medical conditions may increase your risk of developing seborrheic dermatitis.
Treatments
Anti-dandruff shampoos and medicated cleansers and creams are the main treatments for seborrheic dermatitis. Many physicians recommend starting with OTC products designed to treat dandruff and/or seborrheic dermatitis.
Anti-dandruff shampoos that contain pyrithione zinc treat dandruff and seborrheic dermatitis and are typically gentle enough for daily use. You may have to experiment to find the best anti-dandruff shampoo for you. If you have seborrheic dermatitis and sensitive skin or scalp, look for an anti-dandruff shampoo free of common chemical irritants. There may be some trial and error in determining how frequently you need to use an anti-dandruff shampoo to keep your seborrheic dermatitis under control. For days you don’t use an anti-dandruff shampoo, alternate with a mild, fragrance-free shampoo and hair conditioner to help avoid further irritation.
Cleansers that contain pyrithione zinc help control and reduce symptoms of seborrheic dermatitis on the skin. To minimize irritation, alternate between a medicated pyrithione zinc soap bar (zinc soap bar) and a mild, fragrance-free cleanser .
A skin cream that contains a mild corticosteroid such as Hydrocortisone 1% may help relieve itching associated with seborrheic dermatitis. Again, avoid creams that contain fragrance and other common chemical irritants which can further irritate already sensitive skin. Keep skin moisturized with a mild and gentle, fragrance-free moisturizer to help avoid dry itchy skin. Look for products labeled ‘hypoallergenic’ as they tend to be less irritating to sensitive skin. Because not all medicated products are the same, always follow product directions.
When to See a Doctor
If symptoms become unmanageable or there are signs of infection, contact a dermatologist who can prescribe prescription strength products to get your symptoms under control.
https://www.uspharmacist.com/article/is-it-dandruff-or-seborrheic-dermatitis
http://www.pgscience.com/files/pdf/Dr._Thomas_Dawson/TRI_book_chapter_Ch12_Dandruff.pdf
https://www.healthline.com/health/skin-disorders/dandruff-vs-dry-scalp#causes
https://www.medicinenet.com/contact_dermatitis/index.htm
Textbook of Cosmetic Dermatology, Third Edition. Robert Baran, Howard I Maibach, 2005