Betahistine (Serc): uses, side effects and cautions

Betahistine treats the symptoms of Ménière's disease, an inner ear condition. The NHS lists dizziness and a spinning sensation, ringing in the ears, hearing loss and nausea. The emc product information for Serc 8 mg tablets licenses it for vertigo, tinnitus and hearing loss associated with Ménière's syndrome. It is a prescription medicine, taken to reduce how often attacks happen and how troublesome they are, not a cure.

The NHS says it is thought to work by improving blood flow in the inner ear and reducing the build-up of pressure there, which eases symptoms and cuts how often they occur. Betahistine is also an analogue of histamine, and the product information notes that, in theory, it could interact with antihistamines.

Betahistine usually comes as tablets, most often taken 3 times a day. Your doctor decides the amount and how long to take it, and the dose may go up or down according to symptoms. For adults the product information describes a starting dose of two 8 mg tablets three times daily, taken preferably with meals, and maintenance doses generally between 24 and 48 mg a day. It is not recommended below 18 years because of insufficient data. Check the leaflet for your brand.

Swallow tablets with a glass of water, ideally with or after a meal, and leave 6 to 8 hours between doses. If you forget, take it as soon as you remember unless the next dose is nearly due, in which case skip it; never double up.

You may need to take betahistine for some time before symptoms improve, and the NHS says not to stop without speaking to your doctor because the condition may worsen. An extra dose is unlikely to cause problems, but speak to a pharmacist as soon as possible if you take more than prescribed, or call NHS 111 if you cannot reach one or took too much on purpose.

The product information describes a few overdose cases with mild to moderate symptoms, such as nausea, drowsiness and abdominal pain, at doses up to 640 mg, and more serious complications, including convulsion and heart or lung problems, mainly after deliberate overdose with other drugs.

Common effects are nausea, indigestion and headache. The product information adds that mild stomach complaints such as vomiting, abdominal pain and bloating can usually be handled by taking the dose with meals or lowering the dose. Betahistine will not usually affect driving, cycling or machinery, although Ménière's symptoms themselves can; clinical studies of driving ability found no or negligible effect.

Allergic reactions are possible, including anaphylaxis, swelling of the face, hives, rash and itching. Call 999 for a swollen throat or tongue, a raised itchy rash or difficulty breathing, and 111 for any other serious effect. Speak to a pharmacist or doctor if side effects bother you or persist, and keep taking it unless advised otherwise. Suspected side effects can be reported through the Yellow Card scheme.

Most adults can take betahistine. It may not be suitable if you have had an allergic reaction or other serious effect from it, have low blood pressure, have or have had a stomach ulcer, have asthma, or are pregnant or breastfeeding. The product information lists phaeochromocytoma and hypersensitivity as contraindications, advises caution with a history of peptic ulcer, and notes that a few people with bronchial asthma have shown clinical intolerance, so they need careful monitoring.

Tell your doctor about any medical condition before starting.

The NHS names monoamine oxidase inhibitor antidepressants and antihistamines for allergies such as hay fever as medicines that may not mix well. The product information explains that drugs inhibiting MAO, including selegiline, may slow betahistine breakdown, so caution is advised, and that no in-vivo interaction studies have been performed. Food is unrestricted.

It is not usually used during pregnancy because there is little information, and the product information says it is preferable to avoid it as a precaution; if you need it, your doctor will discuss risks and benefits. It is not usually used while breastfeeding because of a risk of effects in the baby, although a doctor may advise it if the benefits outweigh the risks. Tell your doctor if you are pregnant or trying to become pregnant.