Low-dose naltrexone: a novel adjunctive treatment in symptomatic alopecias?

Naltrexone is a competitive antagonist of μ, κ and γ opioid receptors, used for treatment of alcoholism and opioid addiction. Low-dose naltrexone (LDN) is defined as daily doses ranging from 1mg to 5mg. This is purported to have a paradoxical effect that leads to an increase in endogenous opioids, including beta-endorphins, which have anti-inflammatory properties. Theses mechanisms may also justify their possible role in the treatment of inflammatory conditions. The aim of this article is to discuss the use of LDN as an adjuvant therapeutic option in symptomatic alopecias presenting with trichodynia. Trichodynia is defined as scalp discomfort of variable intensity presenting as diffuse or localized dysesthesia and may be described by patients as pain, pruritus, or burning. These are common symptoms in patients with hair loss that negatively impacts quality of life. Scalp discomfort may be refractory to conventional therapies and does not yet have a specific therapeutic guideline. For these cases, LDN would be a possible alternative to be added to the therapeutic arsenal owing to its anti-inflammatory properties, analgesic potential, low cost, and few adverse effects described. Further studies are needed to standardize dosing, better understand its mechanism of action, and evaluate its potential therapeutic indications.