Last updated on November 18th, 2025 at 06:25 pm
Summary
Teriflunomide is a moderately effective platform therapy for treating active MS; it reduces the relapse rate by ~30% and slows the acquisition of disability to a similar degree. It reduces magnetic resonance imaging (MRI) activity by ~70% and slows down brain volume loss, but not to the same degree as highly effective DMTs. Teriflunomide is licensed as a first-line therapy in the UK. It is taken as a daily 14 mg tablet. Although teriflunomide inhibits cell proliferation, it is not an immunosuppressive agent and is classified as an ‘immunomodulatory therapy’.
Teriflunomide has not been associated with opportunistic infections, secondary malignancies, a blunted antibody response to vaccines or lymphopaenia (low lymphocyte counts). Low lymphocyte counts occur in only a small minority of people with MS. In general, teriflunomide is well tolerated, with only a small number of people with MS (< 5%) developing abnormal liver function tests or gastrointestinal symptoms (mainly diarrhoea) that result in them having to stop the therapy. Teriflunomide can cause mild hair thinning that is transient; please note this is not alopecia or baldness and, in my experience, is not a problem for people with MS taking the drug.
Teriflunomide is considered to be potentially teratogenic, i.e. it has the potential to cause foetal abnormalities when women fall pregnant on the drug, which makes it unsuitable for women of childbearing age who are planning to start, or extend, their families. Teriflunomide has a long half-life and hence stays in the body for months. There is a rapid elimination procedure that can remove teriflunomide from the body within days. When teriflunomide is started, the European Medicines Agency (EMA) requires blood monitoring every 4 weeks for 6 months and 2 monthly thereafter. I think these requirements are excessive; many neurologists use the American guidelines, which stipulate monthly tests for 6 months and regularly after that.
It has been difficult to use teriflunomide in the UK, on the NHS, because of its monitoring requirements and associated costs. In clinical practice, teriflunomide seems to be much more effective than suggested by the clinical trial results, which may explain its popularity in other countries. Interestingly, people who start teriflunomide as a second-line or third-line DMT do better than those using it first-line. I have no idea why teriflunomide is more effective after people with MS have failed other DMTs; it may have something to do with its alternative modes of action, for example, its antiviral effects.
Trade name
Aubagio.
Mode of action
Mainly by inhibiting the enzyme dihydroorotate dehydrogenase (DHODH) which affects pyrimidine metabolism in cells.
Efficacy
Moderate.
Class
Maintenance, immunomodulatory.
Immunosuppression
No.
Dosing
14 mg once daily. USA only: 7 mg/day tablet is also licensed (elsewhere, you can take 14 mg tablet on alternate days).
Main adverse events and monitoring requirements
Raised liver enzymes, particularly in people with pre-existing liver disease; possible high blood pressure; rarely, severe hypersensitivity skin reactions.
Liver enzyme assessments every two weeks for 6 months and every 8 weeks thereafter.
Rebaseline MRI scan, ideally after 6 months of treatment.
Pregnancy and breastfeeding: effective contraception is essential while on treatment and during drug elimination before conception. Breastfeeding is contraindicated.