5-HT₁A partial agonist (anxiolytic) Pregnancy: As a precautionary measure it is preferable to avoid the use of buspirone during pregnancy (§4.6). There are no or limited data from use in pregnant women; animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity. The effect on labour and delivery is unknown. Breast-feeding: it is unknown whether buspirone or its metabolites are excreted in human milk — decide whether to discontinue breast-feeding or the medicine.

Buspirone hydrochloride

Brand names: Buspar (legacy)

Buspirone is a non-benzodiazepine anxiolytic used for the short-term management of generalised anxiety disorder.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 5 mg two to three times per day initially; the dosage may be increased every 2-3 days. Usual therapeutic dosage 15 to 30 mg daily in divided doses

Route: Oral

Frequency: Two to three times daily (divided doses)

Max: 45 mg daily in divided doses (the maximum recommended dose)

Source: UK SPC (eMC) for Buspirone Hydrochloride 10 mg Tablets, §4.2 (https://www.medicines.org.uk/emc/product/102436/smpc). The dosage should be individualised for each patient. The stated adult regimen includes the elderly ('Adults (including the elderly)'). Food increases the bioavailability of buspirone — buspirone should be taken at the same time each day and consistently with or without food. Grapefruit juice increases plasma concentrations; patients should avoid consuming large quantities of grapefruit juice. If administered with a potent CYP3A4 inhibitor, the initial dose should be lowered and only increased gradually after medical evaluation (§4.5). HEPATIC IMPAIRMENT: reduced first-pass effect; after a single administration in liver cirrhosis, higher maximum concentrations of unchanged buspirone are seen with an increased half-life — use with caution, titrate individual dosages with care to reduce the chance of central undesirable effects, and consider increased dosages carefully and only after 4-5 days experience with the prior dosage. Severe hepatic impairment is a contraindication (§4.3). PAEDIATRIC: placebo-controlled trials in which 334 patients were treated with buspirone for up to six weeks have not shown buspirone at doses recommended for adults to be an effective treatment for generalised anxiety disorder in patients less than 18 years; plasma concentrations of buspirone and its active metabolite were higher in paediatric patients compared with adults given equivalent doses. No per-kg paediatric dose is stated, hence paedDose is null — verify any under-18 use against a children's formulary. The eMC bundle did not include §4.5 and the US label's interactions section was empty, so the interactions listed below are drawn from the §4.2 and §4.3 statements only — the full UK SPC §4.5 must be checked separately.

Dose adjustments

Renal

Mild to moderate renal insufficiency (creatinine clearance 20-49 mL/min/1.72 m2): a slight increase in buspirone blood levels was seen after single administration without an increase in half-life — administer with caution and a low dosage twice daily is advised; evaluate response and symptoms carefully before any dose increase. Buspirone should NOT be administered to patients with a creatinine clearance < 20 mL/min/1.72 m2, especially not to anuric patients, because increased and untreated levels of buspirone and its metabolites may occur (severe renal impairment is a §4.3 contraindication). In anuric patients, dialysis did not influence buspirone or 1-PP metabolite levels.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known hypersensitivity to buspirone hydrochloride or any ingredient in the tablet
Epilepsy
Acute intoxication with alcohol, hypnotics, analgesics, or antipsychotic drugs
Severe renal or hepatic impairment — severe renal impairment defined as a creatinine clearance of 20 mL/min or below, or a plasma creatinine above 200 micromol/L

Side effects

Dizziness (including lightheadedness), headache and somnolence (very common)
Nervousness, insomnia, disturbance in attention, depression, confusional state, sleep disorder and anger (common)
Nausea, abdominal pain, dry mouth, diarrhoea, constipation, vomiting (common)
Tachycardia and chest pain (common); paraesthesia, blurred vision, abnormal coordination, tremor, tinnitus, musculoskeletal pain, cold sweat, rash and fatigue (common)
Serotonin syndrome, convulsion, extrapyramidal disorder, dystonia, dyskinesia, Parkinsonism, akathisia, syncope, psychotic disorder and hallucination (very rare); angioneurotic oedema and urticaria (rare). Side effects generally occur at the beginning of therapy and usually subside with continued use and/or decreased dosage

Interactions

Potent CYP3A4 inhibitors — if buspirone is given with a potent CYP3A4 inhibitor, the initial dose should be lowered and only increased gradually after medical evaluation (§4.2, §4.5)
Grapefruit juice — increases the plasma concentrations of buspirone; patients should avoid consuming large quantities (§4.2)
Alcohol, hypnotics, analgesics or antipsychotic drugs — acute intoxication with these is a contraindication (§4.3)
Note: §4.5 was not retrieved in this bundle and the US label interactions section was empty — the full interaction profile must be checked separately

Clinical monograph

How it works

It is a partial agonist at 5-HT1A serotonin receptors, modulating serotonergic neurotransmission to produce anxiolysis without significant sedative, muscle-relaxant or dependence-forming effects.

Prescribing in practice

Its anxiolytic effect develops gradually over weeks, so it is unsuitable for acute anxiety or 'as required' relief and patients should be told not to expect an immediate benefit.
It does not prevent or treat benzodiazepine withdrawal, so a patient being switched from a benzodiazepine still needs that drug tapered separately.
Avoid concurrent monoamine oxidase inhibitors and use caution with other serotonergic agents because of the risk of hypertensive or serotonergic reactions.

Monitoring

Monitor anxiety symptom response and tolerability over the first few weeks of treatment.

Counselling the patient

This medicine takes a couple of weeks to start working, so keep taking it regularly rather than only when anxious.
Avoid grapefruit juice, which can raise the amount of drug in your body.
Report severe headache or feeling very agitated.

Evidence & guidelines

Buspirone is an established option for generalised anxiety disorder, distinct from benzodiazepines in lacking dependence liability.

Reference: NICE NG191; NICE CG113; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways