Redness of the scalp: what it could indicate.

Redness on the scalp does not necessarily indicate a dermatosis. Sometimes, it is simply the result of a dry skin, secreting little sebum and having a fragile hydrolipidic film. Furthermore, a deficiency in natural moisturising factors (NMF) is observed in people with dry skin. These are a set of compounds with hygroscopic properties responsible for capturing and retaining water within the stratum corneum, the outermost part of the epidermis. All these factors can make the scalp prone to tightness, itching and, more broadly, redness.

How to take care of a dry scalp?

To alleviate redness and soothe irritations caused by a dry scalp, it is recommended to choose gentle shampoos and hair treatments, containing soothing active ingredients such as bisabolol, phytosterols or rosemary oil. Also favour hydrating and nourishing products, formulated with glycerine, squalane and vegetable oils. A shampoo suitable for dry scalps should be able to gently cleanse, without stripping the hydrolipidic film or attacking the horny layer.

While a dry scalp can be prone to redness, excessive sebum secretion can lead to a similar outcome. Indeed, a sebum-rich environment promotes the proliferation of the fungus Malassezia and the onset of a seborrheic dermatitis. This chronic inflammatory skin condition is characterised by red patches topped with yellowish scales . The dead cells gradually detach from the scalp and resemble dandruff. Non-contagious, seborrheic dermatitis can be difficult to live with due to the intense irritation, itching, and even burning sensations it can cause.

What to do in case of seborrheic dermatitis of the scalp?

The treatment of seborrheic dermatitis primarily involves the use of specialised shampoos prescribed by dermatologists. Those containing selenium sulphide (from 1 to 2.5%) are particularly renowned. Selenium sulphide is a antifungal agent that helps limit the proliferation of Malassezia and thus combat inflammation at its source. Shampoos based on salicylic acid can also be used in cases of seborrheic dermatitis. Thanks to its keratolytic activity, salicylic acid promotes the detachment and elimination of dead skin cells, which contributes to cellular renewal and the healing process of the scalp.

Another common cause of scalp redness is the following: an allergic reaction, that is to say a contact dermatitis. This inflammation caused by an allergen results in red patches and itching. In some cases, eczema causes blisters and then scabs that eventually fall off. Contact dermatitis of the scalp is often due to a poorly tolerated shampoo containing harsh foaming agents (cocamidopropyl betaine), hair dyes (paraphenylenediamine) or perms (ammonium thiosulfate).

How to soothe a scalp irritated by a contact eczema ?

In cases of eczema, it is crucial to consult a dermatologist so that this health professional can prescribe a suitable treatment. Contact dermatitis of the scalp is treated in the same way as that affecting the skin: with topical corticosteroids. These are powerful anti-inflammatory and immunosuppressive agents whose effectiveness in treating eczema has been the subject of numerous studies. In addition, we recommend that you treat your scalp gently , using mild shampoos and massaging it delicately during cleaning. To soothe itching, you can also apply cold compresses, thermal water or certain essential oils such as tea tree essential oil and true lavender essential oil.

Often mistaken for eczema, psoriasis is a condition that can cause redness on the scalp. When it appears in this area, it is characterised by a rounded erythema bordered by scales. This disease is manifested by excessive cell renewal and an accumulation of epidermal cells, leading to local inflammation. Often of genetic origin, psoriasis occurs following a disruption of the immune system and an overly high concentration of T lymphocytes in the skin.

Scalp redness due to psoriasis: what can be done?

An effective management of redness due to psoriasis involves a consultation with a dermatologist. There are currently many treatments for this skin condition, including gels to be applied to the skin, oral medications and non-drug treatments. Among them, we find notably dermocorticoids, vitamin D analogues, such as calcipotriol or calcitriol, anti-proliferatives that act against hyperkeratosis. Finally, UVA or UVB phototherapy has shown real effectiveness in recent years for treating psoriasis and improving the quality of life of patients.

Exposure to the sun is indeed beneficial for morale, but UV rays can also cause a actinic erythema, more commonly known as sunburn. Slightly protected by the hair, the scalp is however not completely safe from sunburns, which manifest as redness, itching, burning sensations, sensitivity to touch and sometimes blisters filled with fluid. These symptoms, usually appearing 8 to 24 hours after exposure, are the result of a inflammatory process leading to a dilation of the blood vessels.

How to alleviate a sunburn on the scalp?

Several measures can be taken to prevent sunburn on the scalp, such as wearing a wide-brimmed hat and limiting exposure to the sun in the early or late parts of the day, when UV rays are less intense. If redness has already set in, the priority is to cool the burn. To do this, the regular application of cold, damp compresses for 15 to 30 minutes is recommended. Furthermore, certain soothing and hydrating ingredients such as aloe vera gel or certain hydrosols like Roman chamomile hydrosol can help to soothe the scalp.

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• BORRADORI L. & al. Dermatology and Sexually Transmitted Infections. Elsevier Masson (2017).

• SCHMELZ M. & al. Skin Barrier Damage and Itch: Review of Mechanisms, Topical Management and Future Directions. Acta Dermato-Venereologica (2019).