Topical Corticosteroids

Topical corticosteroids are first-line therapy for scalp itch associated with inflammatory conditions of the scalp. Clobetasol 0.05% foam or ointment is the preferred formulation. Long-term use of ultrapotent steroids may cause side effects such as folliculitis and telangiectasia. Although prolonged application of topical steroids can cause skin atrophy, the author has never seen atrophy on scalp. In children, always consider systemic absorption [3, 4]. Avoid corticosteroids in case of scalp dysesthesia.

Calcineurin Inhibitors

Tacrolimus 0.1% ointment and pimecrolimus 1% cream are immunomodulators that have anti-inflammatory properties, as well as an antipruritic effect by activating and then desensitizing TRVP-1 on peripheral nerve fibers [5]. A thin layer should be applied twice daily and rubbed gently but completely. Consider the possibility of compounding in a topical solution.

Pruritus is reduced within 48 hours of initial application, and it is safe and effective for prolonged use [6]. Side effects include transient burning or stinging sensations, and it should not be used in cases of infection.

Antihistamines

Although well-known contact sensitizers, topical antihistamines are commonly used. Diphenhydramine 2% lotion or gel is useful in acute allergic reactions. Doxepin 5% cream, a tricyclic antidepressant that is a potent H1 and H2 antagonist, has been shown to significantly reduce pruritus in patients with atopic dermatitis, lichen simplex chronicus, and contact dermatitis [7].

Phosphodiesterase 4 Inhibitors

Crisaborole 2%, a petrolatum-based ointment, is a nonsteroidal phosphodiesterase 4 (PDE4) inhibitor. It has shown efficacy in treatment of skin pruritus associated with atopic dermatitis. Ointment is usually difficult to wash off from the scalp, thus making it an option in localized eczema of the scalp [8, 9].

Salicylates

Salicylates are COX 2 inhibitors that have anti-inflammatory and keratolytic properties. They are effective in cases of pruritus caused by scaly dermatoses such as psoriasis or seborrheic dermatitis.

Salicylic acid is the most commonly used salicylate . Compounded or commercial formulations of salicylic acid 2–6% as ointment, lotion, or shampoo can be utilized. In cases of thick scales, a 6% leave-in lotion or a 3% ointment (applied at night and shampooed in the morning) helps in reducing the hyperkeratosis faster. Shampoo can be utilized in association and for maintenance. Patients must be instructed to apply on wet scalp and rinse after 5–10 minutes. It can be used daily or alternated with normal shampoo, depending on the severity of the disease. A combination of 3% salicylic acid and 1% hydrocortisone can also be used [10].

Strontium Chloride

Strontium chloride is a salt that has an antipruritic and antinociceptive effect by binding and activating the calcium sensing receptor (CaSR). It is useful in histamine and IgE-related itch and also in neuropathic and scar-forming itch. It suppresses inflammation through TNF-α and has antipruritic effect through the protease-activated receptor 2 (PAR-2), thus making it a good option in scarring alopecias , such as LPP. It can be found commercially alone in hydrogel 4% formulation or as a combined formulation of 4% strontium chloride plus 1% hydrocortisone and 2% diphenhydramine . Mild irritation might occur as a side effect [11].

Cannabinoids

Cannabinoid receptor agonists attenuate histamine-related itch. N-palmitoylethanolamine, a cannabinoid receptor CB2 agonist extracted from palm oil, has been compounded into 0.3% cream and shown to reduce pruritus in patients with atopic dermatitis, lichen simplex chronicus, prurigo nodularis, and uremic pruritus. Because of its commercial formulation in cream vehicle, it may be used in cases of xerotic scalps such as elderly scalp, atopic dermatitis, and Sjögren disease [14].

Capsaicin

Topical capsaicin, the active compound in chilli pepper, is an exogenous vanilloid that desensitizes the nerve endings, thus attenuating response to local stimuli. Repeated application of capsaicin inhibits accumulation of calcitonin gene-related peptide (CGRP) and substance P (SP). Capsaicin is commercially available in concentrations of 0.025–0.1%. A burning sensation is common during the first 2 weeks of application. You can avoid this symptom by applying a topical anesthetic before application of capsaicin at the beginning of treatment. Transdermal 8% capsaicin has been approved for use in postherpetic neuralgia. Other possible applications include scalp psoriasis, atopic dermatitis, notalgia paresthetica, lichen simplex chronicus, prurigo nodularis, and uremic pruritus [12, 15].

Coolants

Menthol, camphor, and calamine are coolant agents; their efficacy in treating itch is controversial. Patients who say to improve when taking cold showers or applying ice might benefit from their use. Another mechanism of action involves the ability of menthol to selectively activate κ-opioid receptors and of camphor to act on both transient receptor potential vanilloid (TRVP) 1 and 3 channels, thus making it a good option for treating scalp itch. Menthol 1–7% cream, camphor 0.45% oil, and calamine 3–7.5% are possible options. Common side effects include skin irritation and sensitization; thus, prolonged use is not advised [12, 16].

Herbal Remedies