Feverfew for migraine prevention: mixed evidence, mouth sores and surgery advice

Feverfew, Tanacetum parthenium, grows as a garden plant across the UK, and the name probably refers to an old use for fever. Today it is taken mainly in the hope of preventing migraine. Products include dried leaf capsules and tablets, and extracts. Chewing fresh leaves, once popular, is the form most likely to cause trouble.

The evidence is a mixed picture. A 2020 review of seven studies including 634 people reported inconsistent findings. Some research suggests feverfew might reduce how often migraine headaches occur and ease features such as pain, nausea, vomiting and sensitivity to light and noise, but the trials differ in preparation and dose, which makes them hard to pool.

The NHS page on migraine treatment makes no mention of feverfew. It lists painkillers, triptans, gepants and anti-sickness medicines for attacks, and preventive options such as beta blockers, certain antidepressants and epilepsy medicines, along with acupuncture, relaxation, cognitive behavioural therapy and vitamin B2.

Migraine prevention is usually considered when attacks are frequent or disabling. Feverfew is sometimes trialled by people who prefer a plant product or who cannot take standard preventives. Before relying on it, a GP can check the diagnosis, review triggers and look at medicines already being used.

• Keep a headache diary for a few weeks to show whether any product changes frequency or severity.

• Use a registered product with a stated leaf or extract content rather than loose plant material.

• Stop if mouth irritation, rash or stomach upset appears.

Common side effects are nausea, digestive upset and bloating. Chewing fresh leaves can cause sores and irritation in the mouth, and skin contact may trigger dermatitis in sensitive people. Because feverfew belongs to the daisy family, those who react to ragweed may also react to it.

Do not overuse painkillers while trying a herbal preventive. The NHS warns that taking painkillers on more than two days a week can itself cause more headaches, so a rise in tablet use is a reason to see the GP, not to add products.

Feverfew may interact with medicines used for migraine and may slow blood clotting. The advice is to stop it at least two weeks before surgery, and to tell dental and surgical teams about it. Anyone taking warfarin, a DOAC, aspirin or clopidogrel should talk to a pharmacist before using it.

More generally, the NHS says to check with a pharmacist before taking a herbal medicine if you are on other medicines, and not to stop prescribed medicines without medical guidance.

Feverfew should be avoided in pregnancy because it may affect uterine contractions. Little safety information exists for breastfeeding. The NHS says herbal medicines are not recommended for children, and migraine in children and teenagers should be assessed by a doctor.

Most migraine is benign but some headaches are not. Seek urgent help (999 or A&E) for a sudden, severe thunderclap headache, headache with weakness, speech difficulty, drooping of the face or confusion, or headache after a head injury. See a GP about migraines that are worsening, occurring more than weekly, or hard to control.

Feverfew has been available as a registered traditional herbal medicine as well as a food supplement. A THR mark on the pack shows MHRA assessment of safety, quality and information, though not proof that it works. The MHRA has warned that most herbal products on the UK market are unlicensed and uneven in quality.