Can shampoo cause a rash?

In many people, shampoo is one of the main causes of scalp sensitivity . “Aggressive cleaners or surfactants – present in many shampoos – can wash away the acid mantle from that specific area. In other words, they eliminate the natural acidity that protects the skin of the scalp, leaving it vulnerable to dryness and irritation, ”explains Braú Mateos Carbonero, a pharmacist in the Dermatology group of the Spanish Society of Family and Community Pharmacy (Sefac) .

“It can occur because the shampoo excessively dries the skin, or irritates it in individuals with sensitive skin, for example in some cases due to the use of zinc pyrithione or ichthyol, which are used in dermatitis or desquamative states”, points out José Manuel Carrascosa, member of the Spanish Academy of Dermatology and Venereology (AEDV) .

To start at the beginning, you would have to define a rash , or rash, as irritation or redness of a specific area of ​​the skin – in this case the scalp -, usually accompanied by itching, stinging, burning or tingling and which usually remits in a short space of time.

Other factors and skin pathologies that can cause a rash

“There are many factors that can cause itching or a rash on the scalp. The most frequent are: seborrheic dermatitis, pityriasis capitis (known as dandruff ), psoriasis , atopic dermatitis , allergy to dyes or hairdressing products, or even lice infestation , “says Carrascosa. Mateos adds pathologies such as lichen planus capillary, lupus erythematosus or scleroderma to the list .

The pharmacist details that among the main causes of sensitivity or hypersensitivity of the scalp the following stand out:

  • Climatic conditions:sun, cold, heat or wind.
  • Physical or emotional stress.
  • Chemicalspresent in soaps, cosmetics, water, some drugs and contamination.
  • Hormonal changes: pregnancymenopause, or menstrual cycle .
  • Food allergiesor sensitivities .

“When the natural protective barrier of the skin has been altered by one or more of these factors, microinflammations of the scalp develop, which can also become a main cause of increased sensitivity. This occurs when the skin cells of the scalp become inflamed, increasing vulnerability to irritation, “says the Sefac expert.

Does a dry environment worsen the condition of a sensitive scalp?

“Logically, a dry environment produces greater dehydration of any area of ​​our skin , and let’s not forget that the scalp is part of it,” explains Mateos.

Lack of hydration in the skin can occur in a variety of ways, ranging from typical roughness, peeling, and small cracks, to redness, swelling, constant stiffness, and itching. However, these symptoms vary depending on the severity and location of dehydration.

Carrascosa points out that this worsening of the scalp is more likely in those individuals with a tendency to dry skin, such as atopic dermatitis.

On the contrary, a dry environment favors less washing and, therefore, we avoid the aggressions of hair detergents to the skin and we maintain the oils produced by our body, which are important to preserve flexibility and adequate skin hydration.

Can some shampoos trigger flaking and dandruff?

“Most of us use hair shampoo regularly and that means that its consumption is massive and essential to satisfy our hygiene. In the shampoos we can find some ingredients that would cause affections on the hair and scalp, but are not causing dandruff. On the other hand, they can produce some flaking, especially if they are not eliminated well and there are remains between the hair, or they have a pH that affects the skin tissue, ”says the Sefac expert.

Difference between flaking and dandruff

Every two weeks, the skin cells of a healthy scalp are naturally renewed and removed during washing and brushing in the form of tiny, invisible scales. However, when the cell renewal process is accelerated, excessive desquamation of the scalp occurs , forming groups of dead cells (called dandruff ). These scales are large, white or yellow in color, and can become very itchy.

Instead, peeling is a natural process of renewal of the cells of the scalp . Sometimes it is too dry and excessive flaking occurs. In this case, the scales are transparent, small and dry. It is also usually accompanied by itching.

Shampoos that over-dry the scalp, particularly in predisposed individuals, may promote flaking or dandruff.

Risks of using unsuitable shampoo

Choosing a shampoo with scientific criteria is a difficult problem for the general population, given the large number of options that are usually found at points of sale, Mateos acknowledges. Shampoos for hair damaged by dyes and perms, for dry, oily, dandruff, dull, curly, volumeless, sensitive, rough, children’s hair are stacked on any pharmacy or perfumery counter … It’s a chore It is difficult to choose the right one, but in case of presenting any reaction to any of them, it is interesting to specify and avoid successive uses.

It is also necessary to assess not only the pathological criteria, but the cosmetic wishes of the patient. The first thing is to know if the scalp is sick or healthy , since the patient needs a shampoo to treat this pathology. From pediculosis to psoriasis, from impetigo to dandruff, from fungal infection to atopic dermatitis. “In the event that a product exacerbates the symptoms, we must inform the nearest physician, the pharmacist or the corresponding dermatologist. They will know how to guide us and decide what measures we should adopt and what products to discard, “says the Sefac expert.

Recommendations if you suffer a rash on the scalp

Carrascosa and Mateos offer the following recommendations if a rash appears on the scalp:

  1. The first common sense action would be to find another shampoo. Try to buy a pharmacy, which does not contain perfumes, with mild cleansers. It may also be due to the fact that, for example, a therapeutic shampoo, anti-dandruff or flaking is used in an individual with very sensitive skin. This can also promote itching. Undoubtedly, if we associate the itch or rash to a specific product, we must stop using it immediately, and if the problem persists, go to the nearest pharmacist or dermatologist.
  2. We must be aware of the existence of very effective treatments, such as using a mild shampoo, abundantly lightening the hair and not using a keratolytic shampoo regularly. There are also cosmetic products that can be applied after washing your hair to soothe sensitive scalps.
  3. We must check the amount of shampoo we use, since a large dose in each wash increases the probability that the residues irritate the skin of the scalp. Also, even so-called neutral shampoos can contain some chemicals that cause mild allergic reactions, making the problem worse.
  4. It is important to avoid stressful situations, since it can cause an increase in sensitivity.

Frequent queries

Carrascosa acknowledges that GPs or pharmacists are likely to receive more queries about a scalp rash than dermatologists. “In the pharmacy the consultations are varied and a very frequent one is about the proper use of a shampoo, whether there is a rash or not,” says Mateos. To answer questions, the pharmacist provides the answers to the most frequent:

  • The important thing is to know that when there is no alteration of the scalp or hair,you should simply use a cleansing shampoo, without pharmacological additives of any kind.
  • A shampoo can contain colors or aromas, but it has no contraindication if you are not allergic.
  • Treatment shampoo must be purchased from the pharmacy, as it ensures the quality of the ingredients.
  • What you can expect from a shampoo is an aid in the treatment of pathologies, but only symptomatically, not curatively.
  • Dandruffcan go away with anti-dandruff shampoos as long as they are used daily for as long as there are symptoms.
  • Fatdoes not disappear or decrease with shampoos, since it is governed by hormonal impulses. Only greater cleanliness and better appearance are achieved.
  • When improvement occurs, treatment should be continued on alternate days, alternating with a mild shampoo without specific additions.
  • Hygiene shampoosare used by applying a small amount, rinsing and repeating the application. It must be accompanied by a gentle massage.
  • Treatment shampoosrequire a second application after the first application, in which the product is allowed to act on the scalp for five to seven minutes . This allows you to better achieve your goal.
  • The sensitive scalpis a true pathology that requires an extra-fat shampoo, with ingredients without risk of sensitization and with the addition of anti-inflammatory substances. Shampoo for sensitive scalp must be specific and purchased from a pharmacy.


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