Clemastine Fumarate


  • Also known as: Tavist
  • Route and Dose of Administration: Oral tablet (10.72 mg daily)
  • Type: Remyelination; immunomodulator
  • Emerging Treatment for: Relapsing-Remitting Multiple Sclerosis (RRMS), acute demyelinating optic neuritis
  • Status: Completed Phase II Clinical trial

How it Works

Clemastine Fumarate is an oral antihistamine that works by promoting the development of myelin-making cells, called oligodendrocytes. Studies have also shown clemastine’s effects in suppressing the immune system of mice and people without MS. Clemastine is an over the counter allergy medication, however, doses used in the MS clinical trial exceed the daily maximum recommendation.

Research and Results

ReBUILD: Phase II Trial

A phase II single-center, randomized, double-blind, placebo-controlled clinical trial called ReBUILD tested the safety and efficacy of clemastine fumarate in 50 individuals with RRMS. Participants were given oral clemastine fumarate (10.72 mg) daily or a placebo for the first 90 days and for the second 60 days, those that received the treatment were switched to placebo and vice-versa.The primary endpoint measured the speed at which messages were transmitted between the eye and the brain in response to stimulation. Delays in transmission occur when myelin is damaged and reduced delays are an indication of myelin repair. The trial met its primary endpoint which reduced delays by 1.7 milliseconds per eye. The results of the clinical trial were published in the medical journal The Lancet. A larger clinical trial is needed before doctors can recommend this treatment for people with MS.

ReCOVER: Phase II Trial

A phase II randomized, double-blind, parallel-group, placebo-controlled trial to assess the effect of clemastine as a myelin repair agent and its potential for the neuroprotection in people with acute demyelinating optic neuritis. The study will also evaluate the tolerability of clemastine, originally approved as first-generation antihistamine, in people with acute myelin-damaging optic neuritis. 

The anticipated completion date for the trial is August 2022.


Green AJ et al. Clemastine fumarate as a remyelinating therapy for multiple sclerosis (ReBUILD): a randomised, controlled, double-blind, crossover trial. Lancet. 2017; 390: 2481-89.