Buspirone Side Effects
Buspirone's most common side effects include dizziness (12%), nausea (8%), headache (6%), nervousness (5%), and lightheadedness (3%), with approximately 10% of patients discontinuing treatment due to adverse events, primarily CNS disturbances. 1
Most Common Side Effects (≥1% incidence)
The FDA-approved labeling identifies the following frequently reported adverse effects in controlled clinical trials 1:
Central Nervous System Effects
- Dizziness (12%) - most common side effect
- Drowsiness (10%)
- Nervousness (5%)
- Insomnia (3%)
- Lightheadedness (3%)
- Decreased concentration (2%)
- Excitement (2%)
- Anger/hostility (2%)
- Confusion (2%) 1
Gastrointestinal Effects
- Nausea (8%) - second most common side effect
- Dry mouth (3-4%)
- Abdominal/gastric distress (2%)
- Diarrhea (2%)
- Constipation (1-2%)
- Vomiting (1-2%) 1
Other Common Effects
- Headache (6%)
- Fatigue (4%)
- Weakness (2%)
- Tachycardia/palpitations (1%)
- Blurred vision (2%) 1
Reasons for Treatment Discontinuation
Approximately 10% of patients discontinued buspirone in premarketing trials due to adverse events 1:
- CNS disturbances (3.4%): primarily dizziness, insomnia, nervousness, drowsiness, and lightheadedness
- GI disturbances (1.2%): primarily nausea
- Miscellaneous (1.1%): primarily headache and fatigue
- Multiple complaints (3.4%) 1
Less Common but Notable Side Effects
Infrequent Effects (1/100 to 1/1,000 patients) 1
- Cardiovascular: syncope, hypotension, hypertension
- CNS: depersonalization, dysphoria, euphoria, akathisia, hallucinations, involuntary movements, suicidal ideation, seizures
- Sexual function: decreased or increased libido
- Hepatic: increases in liver enzymes (SGOT, SGPT)
- Musculoskeletal: muscle cramps, muscle spasms, rigid/stiff muscles 1
Rare Effects (<1/1,000 patients) 1
- Serious cardiovascular: cerebrovascular accident, congestive heart failure, myocardial infarction, cardiomyopathy, bradycardia
- CNS: stupor, slurred speech, psychosis
- Hematologic: eosinophilia, leukopenia, thrombocytopenia 1
Postmarketing Reports
Additional adverse effects reported since market introduction include 1:
- Allergic reactions (including urticaria)
- Angioedema
- Extrapyramidal symptoms and dyskinesias (acute and tardive)
- Cogwheel rigidity and parkinsonism
- Serotonin syndrome
- Restless leg syndrome
- Visual changes (including tunnel vision)
- Urinary retention 1
Important Clinical Distinctions
Advantages Over Benzodiazepines
Buspirone notably lacks several side effects common to benzodiazepines 2, 3:
- No sedation (or minimal sedation)
- No muscle relaxation
- No anticonvulsant effects
- No psychomotor impairment when combined with alcohol or given alone
- No abuse, dependence, or withdrawal symptoms reported 2, 3, 4
Neurochemical Effects
Buspirone increases peripheral levels of noradrenaline, dopamine, and free serotonin, which may contribute to both therapeutic and adverse effects 5. Small but significant decreases in systolic blood pressure and heart rate have been observed 5.
Critical Prescribing Considerations
Buspirone requires 2-4 weeks to become effective and is useful only in patients with mild to moderate agitation 6. The initial dosage typically starts at 5 mg twice daily, with a maximum recommended dosage of 20 mg three times daily 6.
Common Pitfall
Patients with previous long-term benzodiazepine exposure may experience reduced efficacy and increased dropout rates with buspirone, as the drug is not cross-tolerant with benzodiazepines 7. This is particularly important when transitioning patients from benzodiazepine therapy.