What are the side effects of betahistine?

Betahistine Side Effects

The most common side effects of betahistine include headache, gastrointestinal symptoms such as nausea, vomiting and abdominal pain, and cutaneous hypersensitivity reactions like rash, pruritus, and urticaria. 1, 2

Common Side Effects

• Gastrointestinal symptoms are frequently reported, including nausea, vomiting, and unspecific abdominal pain 2
• Cutaneous hypersensitivity reactions such as rash, pruritus (itching), and urticaria (hives) are among the most commonly reported adverse effects, but are typically mild and self-limiting 2
• Headache is a common side effect that may occur following betahistine administration 1, 2
• Dizziness may paradoxically occur in some patients taking betahistine 1

Serious Adverse Effects

• Severe systemic reactions are rare but may include flushing, bronchial constriction, marked hypertension or hypotension 1
• Anaphylactoid reactions have been reported but are extremely rare; no anaphylactic reactions with fatal outcomes have been documented 2
• Stevens-Johnson syndrome has been reported in at least one case 2
• Hepatobiliary involvement has been reported in some cases, including increases in liver enzymes (alkaline phosphatase, gamma-glutamyltransferase, alanine and aspartate aminotransferase) 2
• Betahistine is completely contraindicated in patients with pheochromocytoma 3, 4

Overdosage Concerns

• Overdosage may cause severe symptoms including vasomotor collapse, shock, and potentially death 1
• Large doses may lead to severe occipital headache, blurred vision, anginal pain, rapid drop in blood pressure, and cyanosis of the face 1
• In case of severe reactions due to overdose, epinephrine injection may be required as emergency treatment 1

Special Populations and Considerations

• Betahistine should be used with caution in patients with asthma and history of peptic ulcer disease 3, 4
• There are no specific pediatric dosing guidelines available, and safety in children has not been well established 4
• The drug has been found to be generally well-tolerated with a similar risk of adverse effects to placebo in clinical trials for tinnitus 5
• When compared to other vestibular suppressants, betahistine has shown fewer sedative effects, which may be advantageous in certain patient populations 6

Clinical Context

• Betahistine is not routinely recommended for treatment of benign paroxysmal positional vertigo (BPPV), as vestibular suppressant medications in general have not shown significant benefit over particle repositioning maneuvers 7
• For severe or refractory symptoms in conditions like irritable bowel syndrome, vigilance for serotonin syndrome is required when betahistine is used in combination with other serotonergic drugs 7
• Higher doses of betahistine (72 mg/day) may be more effective for intractable dizziness in some patients with unilateral vestibulopathy, but may also increase the risk of side effects 8

Betahistine is generally well-tolerated with most adverse effects being mild and reversible upon discontinuation of the drug. However, clinicians should monitor patients for potential serious reactions, especially in those with pre-existing conditions like asthma or peptic ulcer disease.