A wide variety of different conditions may cause a dry scalp. In this article, we will review the most common causes of a dry scalp, related conditions, and treatment options. The most common cause of a dry, itchy, flaky, scaly, irritated, and red scalp is seborrheic dermatitis. When seborrheic dermatitis is only within the scalp then the condition is known as dandruff. When it involves the scalp and specific parts of the face, we generally consider it a little more severe than dandruff and is most appropriately referred to as seborrheic dermatitis or even psoriasis depending upon involvement of other parts of the body. Another very common cause for a dry scalp is eczema. This condition may also affect other parts of the body with a dry, flaky, scaly, red, and itchy rash especially the folds of the body including the inside of the arms, behind the knees, and lower legs during the wintertime.
The most typical symptom of a dry scalp is self-explanatory, a dry scalp! Specifically, many people also report they have dryness and flaking of other areas on the body including the eyebrow area, ears, beard, or face just to name a few. In this setting, the most likely condition would be seborrheic dermatitis or eczema depending on the clinical features.
The most common cause of a dry itchy scalp is dandruff which is a very mild form of seborrheic dermatitis. Additional skin diseases which can cause an itchy, dry, flaky, irritated, red scalp include eczema, scalp psoriasis, or sometimes skin allergies.1 These allergic substances which most commonly cause a rash are include metals like nickel or cobalt, a fragrance additive called Basalm of Peru, fragrance mix, and propylene glycol which is an added stabilizer in cosmetic agents. Nickel or cobalt can be present in trace amounts within metal objects used to style the hair including barrettes, claps, and ties. Fragrance additives and propylene glycol is usually incorporated in cosmetic products such as shampoos, conditioners, or gels.2 Sometimes, the chemicals in hair dye called paraphenylenediamine (PPD for short) also causes a reaction on the scalp. Rarely, more dangerous autoimmune conditions including a disease called dermatomyositis, may cause an itchy, flaky, scaly scalp. Thankfully, this condition is extremely rare affecting about 10 in 1,000,000 people.3 Nerve-related conditions called neuropathic itch can cause symptoms of scalp itching and irritation but no rash or scaling is present. In this situation, the symptoms come from nerve endings not from within the skin itself. A superficial fungal infection of the hair shafts can also cause a scaly, flaky, very dry scalp but may spread to other skin surfaces. This contagious condition is called tinea capitis and usually occurs children with a darker skin and curly hair.
Although the scalp is dry and flaky, you would think a conditioner would improve the symptoms. However, this is not always the case. Treatments for eczema, dandruff, seborrheic dermatitis, fungal infections, and psoriasis can improve the symptoms. Many of the over-the-counter products include pyrithione zinc, selenium sulfide, or coal tar. Alternatively, in cases of eczema, skin allergies, and sensitive skin, avoidance of any irritating substances or allergic materials should be the first line treatment. This includes using a fragrance-free shampoo, avoidance of metal objects to style the hair, and hair dyes free of paraphenylenediamine.