Scalp Allergy: How to Alleviate It?

1 - Consult a doctor.

Following an allergic reaction of the scalp, especially if it is quite severe or persistent, it is always advisable to seek advice from a health professional. In addition to confirming that it is indeed an allergic reaction and not a chronic skin problem such as atopic dermatitis or psoriasis, this step allows for the determination of a treatment to soothe the reaction and prevent its recurrence. During the appointment, the doctor may also suggest performing skin tests to identify the allergen involved and facilitate its removal from the hair care routine. Most often, the medical prescription leans towards antihistamines or corticosteroids, even though these are not the only treatments capable of combating skin allergies.

Antihistamines : These medications are effective in blocking histamine, the inflammatory molecule involved in allergic reactions. Indeed, by binding to specific receptors, histamine stimulates vasodilation and sensory nerves, thereby triggering redness and itching. By preventing this action, antihistamines quickly alleviate symptoms. They are often prescribed orally, even when the allergy affects the scalp.
Corticosteroids : Creams, lotions, or gels based on cortisone are useful for controlling local inflammation of the scalp. Indeed, contrary to popular belief, some formulas are suitable for the scalp area and do not alter hair fibers. From a mechanistic point of view, corticosteroids reduce the activity of the immune system by limiting the proliferation of inflammatory cells and slowing the release of pro-inflammatory cytokines, partly responsible for allergic symptoms. In some cases, corticosteroids can be used in synergy with antihistamines.

Practical Advice:
Corticosteroids should not be used long-term, as they risk weakening the skin.
Some antihistamines can cause drowsiness, which is why it is preferable to take these medications in the evening.

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2 - Identify the responsible allergen.

To effectively manage an allergy, it is crucial to know which allergen your skin is sensitive to. This investigation can be more complex than it seems, as the scalp is daily exposed to numerous irritants. To identify the allergen, it is recommended to individually test each of the hair care products you use on the inside of your elbow or behind your ear. If, after 48 hours, you observe no reaction, it is unlikely that this product is the culprit. On the other hand, if redness, itching, or irritation occurs, it is advisable to remove it from your skincare routine.

If this causality test does not identify the cause of the scalp allergy and it persists, it may be necessary to consult an allergist for more extensive examinations.

The table below lists the main allergens responsible for scalp allergies, accompanied by some statistics on the prevalence of sensitivity within an allergic population. These figures come from the American Contact Dermatitis Society (ACDS) and were obtained with 226 patients.

Allergen	Sensitivity of the Population
Nickel	23.8 %
Cobalt	21.0 %
Potassium Dichromate	8.3%
Peruvian Balsam	18.2 %
Blend of Fragrances	14.4%
Carba mix	11.6 %
Propylene Glycol	8.8%
Ammonium Persulfate	7.2%
Methyldibromoglutaronitrile	5.0 %
Quaternium-15	3.3%

Les principaux allergènes impliqués dans les allergies du cuir chevelu d'après l'ACDS.

3 - Adapt your hair care routine.

To alleviate itching and prevent future allergies, it is advisable to favor products dedicated to sensitive or allergic scalps, soothing and non-drying, formulated in a way to minimize the risks of skin allergy. Alcohols, perfumes, and parabens should thus be avoided. Moreover, to not further weaken your scalp, try to limit the frequency of your shampoos to one to three times a week. During rinsing, opt for lukewarm water rather than hot, as heat can exacerbate inflammation and itching. The same applies when drying your hair. If your hairdryer allows, set it to the lowest temperature and hold it 30 cm away from your scalp.

To soothe a scalp allergy, it is also recommended to avoid coloring your hair, at least while the allergy is active. Hair dye products often contain allergens, such as paraphenylenediamine (PPD), a molecule that facilitates the penetration of the coloring agent into the hair fiber but is also associated with numerous allergic reactions. A study conducted among 1320 people revealed that 11.8% of participants showed sensitivity to PPD, thus highlighting its strong allergenic potential. Furthermore, before re-coloring your hair, it is important to ensure that it was not the cause of the previously experienced symptoms.

4 - Apply cold.

The application of cold is a simple yet effective method to alleviate the symptoms of an allergic reaction, particularly itching and burning sensations. Cold induces vasoconstriction, temporarily reducing blood flow and limiting the arrival of inflammatory mediators responsible for the symptoms. To do this, you can dampen a washcloth with cold water before placing it in the freezer for about ten minutes. Then apply the washcloth to your scalp for relief.

Another option: spray a thermal water that you have kept in the refrigerator. In addition to having a refreshing effect, this method allows you to take advantage of the soothing and regenerative virtues of thermal water, rich in trace elements. Lastly, more simply, you can wrap an ice cube in a clean cloth and gently apply it in circular motions to your scalp. However, be careful not to apply the ice cube directly to your scalp as this could significantly irritate it.

Even though the effects of cold are temporary, this technique offers quick relief and can be used several times a day.

5 - Use certain hydrosols and essential oils.

Certain essential oils, such as the tea tree essential oil (INCI: Melaleuca Alternifolia Leaf Oil), the true lavender essential oil (INCI: Lavendula Angustifolia Oil) or the ginger essential oil (INCI: Zingiber Officinale Root Oil), and hydrosols, like the Roman chamomile hydrosol (INCI: Anthemis Nobilis Flower Water), the cornflower hydrosol (INCI: Centaurea Cyanus Flower Water) or the Damask rose hydrosol (INCI: Rosa Damascena Flower Water), are renowned for their soothing properties. They work via various mechanisms to reduce scalp inflammation and soothe the skin.

Exercise caution if you decide to use an essential oil. These treatments are highly concentrated in active ingredients, so it is crucial to dilute them in a carrier oil before application. Opt for light carrier oils, such as jojoba oil or grape seed oil, which have a dry touch that is particularly suited to the scalp and prevents it from becoming greasy. A concentration of 1 to 2% is generally sufficient, which equates to 1 to 2 drops of essential oil in 98 to 99 drops of carrier oil, or 1 to 2 mL of essential oil in 98 to 99 mL of carrier oil. Apply this mixture with light massages, leave it on for 15 to 20 minutes, then rinse thoroughly with a gentle shampoo. Hydrosols, on the other hand, can be sprayed directly onto the scalp. For an even more soothing effect, you can store them in the refrigerator.