Betahistine: Histamine analogue for the treatment of vertigo and Meniere's disease

Betahistine is a histamine analogue used for the treatment of vertigo and other symptoms of Meniere's disease and vestibular conditions. The active ingredient is available in Germany under the brand name Aequamen and as a generic, and is one of the most frequently prescribed active ingredients in ENT medicine and neuro-otology. Betahistine is administered orally as a tablet or solution and is classified as a prescription-only medicine.

Meniere's disease is a condition of the inner ear characterised by episodic rotational vertigo, unilateral hearing loss, tinnitus (ringing in the ears), and a feeling of pressure in the ear. The condition is based on an endolymphatic hydrops, an accumulation of fluid in the membranous labyrinth of the inner ear. Betahistine is used specifically to relieve these symptoms and reduce the frequency of vertigo attacks. Despite decades of clinical experience, its precise efficacy in randomised controlled studies remains a subject of scientific discussion.

Mechanism of Action

The mechanism of action of betahistine is complex and not fully elucidated. Betahistine acts as a weak agonist at histamine H1 receptors and as a potent antagonist at presynaptic histamine H3 receptors (autoreceptors). Through this dual action, betahistine influences histamine release and the vascular and neuronal functions regulated thereby in the inner ear.

Promoting blood flow in the inner ear: Through activation of H1 receptors on the blood vessels of the inner ear, betahistine causes local vasodilation of the stria vascularis and the precapillary sphincters in the inner ear. This improves microcirculation in cochlear and vestibular tissue and is intended to reduce endolymphatic pressure by improving lymphatic drainage. Improved microcirculation can counteract the endolymphatic hydrops considered the pathophysiological basis of Meniere's disease.

Modulation of the vestibular system: As an H3 antagonist, betahistine inhibits presynaptic histamine autoreceptors in the vestibular nuclei of the brainstem. This leads to increased histamine release and thus to modulation of neuronal activity in the vestibular nuclei. It is assumed that this effect normalises vestibular signals and reduces vertigo sensitivity.

Cochlear effect: In the cochlea, betahistine is intended to stabilise ion pump activity through improved blood supply to the stria vascularis, thereby normalising endolymphatic composition, which can counteract hearing loss.

Indications

• Meniere's disease: Reduction of the frequency and severity of vertigo attacks; relief of tinnitus, feeling of pressure in the ear, and fluctuating hearing loss
• Vestibular vertigo: Various forms of vestibularly caused vertigo (vestibular neuritis, labyrinthitis) as supportive therapy
• Off-label applications: Central vertigo in vascular conditions; vertigo in brainstem lesions; tolerability review in elderly patients with multifactorial vertigo

Dosage and Administration

Standard dosage adults: 8 to 16 mg three times daily (daily dose 24 to 48 mg). Some guidelines recommend higher doses of up to 48 mg three times daily (144 mg/day) for Meniere's disease, which have been better investigated in studies and can be used in severe cases.

Tablets (8 mg and 16 mg): For oral ingestion with meals; taking with a meal reduces gastrointestinal side effects and slightly slows absorption without relevantly altering bioavailability. Solution: Dose according to the prescribed individual dose.

A treatment duration of at least 3 months is recommended to be able to assess efficacy, as betahistine does not act immediately during an acute vertigo attack but is used prophylactically to prevent attacks. If response is insufficient after 6 months, therapy should be critically reviewed.

Side Effects

Betahistine is generally considered well tolerated, which is one of its main advantages over older antivertiginous drugs (e.g. cinnarizine with strong sedation).

Common: Nausea, stomach complaints, bloating, and upper abdominal pain, particularly when taken on an empty stomach. Gastrointestinal tolerability can be significantly improved by taking with meals.

Occasional: Headache (can be explained by the vasodilatory effect), skin reactions such as pruritus, urticaria, or exanthema.

Rare: Anaphylactic reactions (as an H1 agonist, betahistine can theoretically trigger allergic reactions), angioedema. As betahistine promotes histamine release, particular caution is required with known histamine intolerance or mastocytosis.

Compared to other vertigo remedies: No relevant sedation, no anticholinergic effects (unlike scopolamine or dimenhydrinate), no extrapyramidal side effects (unlike metoclopramide). These properties make betahistine particularly attractive for long-term use and elderly patients.

Interactions

Antihistamines (H1 blockers): Classical antihistamines such as cetirizine, loratadine, or dimenhydrinate can weaken the effect of betahistine, as they act antagonistically at H1 receptors. The concurrent use of classical H1 antihistamines and betahistine is pharmacologically of little benefit and should be avoided.

MAO inhibitors: Betahistine is broken down via monoamine oxidase; MAO inhibitors (tranylcypromine, phenelzine, irreversible MAO inhibitors) can slow the breakdown of betahistine and increase its plasma levels. The combination should be avoided.

Antiasthmatic drugs (beta-2 agonists and theophylline): Theoretical interaction via histaminergic mechanisms; clinical significance is not, however, clearly established.

Food: Meals slightly slow absorption; this effect is, however, not clinically relevant and concurrent ingestion with food is even recommended to improve gastric tolerability.

Special Notes

Bronchial asthma: As betahistine can promote bronchoconstriction via H1 receptors, caution is required in asthma patients. Betahistine should be used in bronchial asthma only after careful benefit-risk assessment and under close monitoring.

Peptic ulcer: Histamine analogues can fundamentally affect gastric acid secretion. Patients with known gastric or duodenal ulcers should take betahistine with caution.

Phaeochromocytoma: Betahistine is contraindicated in phaeochromocytoma (adrenal tumour with catecholamine hypersecretion), as interaction with histamine receptors can trigger hypertensive crises.

Pregnancy and breastfeeding: Adequate data on safety during pregnancy are lacking. Betahistine should be used during pregnancy only in cases of urgent clinical need and after medical assessment. It is unclear whether betahistine passes into breast milk; breastfeeding should be discussed with the treating physician during therapy.

Children: Betahistine is not recommended for children and adolescents under 18 years of age, as adequate data on safety and efficacy in this age group are lacking.

Efficacy discussion: The randomised, double-blind BEMED study (2016) found no significant difference between betahistine and placebo in Meniere's disease. International guidelines and clinical experience continue to support its use but emphasise the limited evidence. The therapy decision should be made individually and in close consultation with the treating physician.

Frequently Asked Questions

How long must betahistine be taken?

Betahistine only exerts its prophylactic effect after several weeks of continuous intake. Assessment of efficacy should occur at the earliest after 3 months. With good response, long-term therapy is recommended; the optimal duration of therapy is individual and depends on the course of the disease.

Can betahistine immediately relieve acute vertigo?

No. Betahistine is not an acutely effective antivertiginous drug for the vertigo attack. Other agents are used for acute attack treatment (e.g. dimenhydrinate). Betahistine acts prophylactically and long-term to reduce the frequency and intensity of attacks.

What is Meniere's disease and how is it related to betahistine?

Meniere's disease is a condition of the inner ear with episodic rotational vertigo, fluctuating hearing loss, tinnitus, and ear pressure. The cause lies in an endolymphatic hydrops. Betahistine is intended to reduce the accumulation of endolymph by improving inner ear blood flow and modulating vestibular signalling pathways, thus relieving symptoms.

Is betahistine the same as histamine?

No. Betahistine is a structural analogue of histamine with a different receptor binding profile: as an H3 antagonist and weak H1 agonist, it acts specifically on the inner ear and vestibular structures, without triggering the typical systemic histamine effects (allergic reactions, severe bronchoconstriction) at therapeutic doses.

References

• Product information Aequamen (Solvay Pharmaceuticals), as of 2024
• Strupp M et al.: Betahistin in the treatment of Meniere's disease. New England Journal of Medicine, 2016
• Lempert T et al.: S1 guideline Meniere's disease of the German Society for Neurology (DGN), 2021
• European Medicines Agency (EMA): Betahistine product monograph
• Lacour M, Tighilet B: Betahistine treatment in a cat model of vestibular pathology. Acta Oto-laryngologica, 1997