Buspirone: uses, side effects and what to know

Buspirone is an anxiolytic (anti-anxiety) medicine taken by mouth as 5, 7.5, 10, 15 and 30 mg tablets. Its brand name was BuSpar: per MedlinePlus, that brand is no longer on the market, but generic buspirone is still available.

It is a prescription medicine. The FDA label states that buspirone is not a controlled substance and is not chemically or pharmacologically related to the benzodiazepines, such as alprazolam (Xanax) or clonazepam.

Per the FDA label, buspirone is approved for the management of anxiety disorders and for the short-term relief of the symptoms of anxiety. Its efficacy was shown in trials of patients whose diagnosis roughly matched generalized anxiety disorder (GAD): excessive, hard-to-control worry, tension, restlessness and insomnia.

The label notes that ordinary anxiety or tension from everyday stress usually does not need an anti-anxiety medicine. It has no other approved uses on the label; any other use would be off-label and is the doctor's call for your situation.

The FDA label says the exact mechanism of buspirone is unknown. It binds strongly to one type of serotonin receptor (5-HT1A) and moderately to dopamine receptors, and it does not act on benzodiazepine receptors. The label also notes that it does not relax muscles or prevent seizures, and it is less sedating than other anti-anxiety medicines.

If anxiety is what you feel, the doctor first works out which kind it is and then explains your options, with or without medicine. Read more about anxiety.

Dose. Per the FDA label, adults start at 15 mg a day (7.5 mg twice a day). The dose can be raised by 5 mg a day every 2 to 3 days, up to a maximum of 60 mg a day; in trials, 20 to 30 mg a day in divided doses was most common. The doctor decides the dose and adjusts it gradually based on how you respond; do not change it on your own.

Same way with food every time. Food increases how much buspirone you absorb. So the label says to take it either always with food or always without food, the same way each time.

How long it takes. According to the National Institute of Mental Health (NIMH), buspirone must be taken every day for 3 to 4 weeks to reach its full effect, and it does not work when taken only when you feel anxious. MedlinePlus adds that it may take several weeks to reach the dose that works for you.

Longer-term use. The label states that its effectiveness for more than 3 to 4 weeks has not been demonstrated in controlled trials; if it is used longer, the doctor checks with you from time to time whether it is still helping.

According to the FDA label and MedlinePlus, the most common buspirone side effects are:

The buspirone label has no boxed warning (the FDA's strongest warning). Even so, MedlinePlus says to call your doctor right away for an allergic reaction (hives, swelling of the face, mouth or throat), a fast or irregular heartbeat, blurred vision or shaking you cannot control.

Serotonin syndrome. It is rare but serious. The label warns it can happen with buspirone, especially combined with other medicines that raise serotonin, such as SSRIs, SNRIs or triptans for migraine. Signs include agitation, hallucinations, fever, sweating, a racing heart, tremor, muscle stiffness and seizures. If you have them, go to the ER.

Restlessness. The label describes unusual restlessness in some people shortly after starting it. If it happens to you, tell the doctor.

Driving. It is less sedating than other anti-anxiety medicines, but its effect varies from person to person: do not drive or use machinery until you know how it affects you.

Do not combine it with MAO inhibitors (MAOIs) for depression, or within 14 days before or after one, because of a higher risk of serotonin syndrome and elevated blood pressure, per the label. Nor is it started in someone receiving linezolid or intravenous methylene blue. Do not take it if you are allergic to buspirone.

Grapefruit and other medicines. Buspirone is processed in the liver by an enzyme called CYP3A4. Per the label, large amounts of grapefruit juice, erythromycin, itraconazole, diltiazem and verapamil raise its blood levels a lot and can increase side effects; ketoconazole and ritonavir may also raise them. Rifampin, dexamethasone and some seizure medicines (phenytoin, phenobarbital, carbamazepine) lower them, and it may lose effect. Avoid drinking large amounts of grapefruit juice.

Alcohol. The label says it is prudent to avoid alcohol with it, and MedlinePlus explains that alcohol can add to the drowsiness it causes. Tell the doctor every medicine and supplement you take.

If you are pregnant, planning a pregnancy or breastfeeding, the decision is made with the doctor. Per the FDA label, there are no adequate studies in pregnant women, so it is used in pregnancy only if clearly needed. It is not known whether it passes into human breast milk (it does in rats), and the label advises avoiding it while breastfeeding if possible. If you become pregnant while taking it, tell the doctor.

Per the FDA label, in two 6-week trials of 559 children and teens aged 6 to 17 with generalized anxiety disorder, buspirone did not work better than placebo. If your child has anxiety, the doctor evaluates them with a parent or guardian on camera and explains the options.

Both are used for anxiety, but they are very different, per the buspirone label, the FDA and the NIMH:

• How they are taken: per the NIMH, buspirone must be taken every day for 3 to 4 weeks to reach its full effect, while benzodiazepines are sometimes used as needed for severe anxiety in the short term.
• Control: buspirone is not a controlled substance and showed no potential for abuse, tolerance or dependence in studies; benzodiazepines are controlled substances and carry an FDA boxed warning on abuse, addiction, dependence and withdrawal.
• Sedation: buspirone is less sedating and does not relax muscles.

Important: buspirone does not relieve withdrawal symptoms from benzodiazepines or other sedatives. If you take a benzodiazepine, do not stop it suddenly on your own: the label says to taper it gradually before starting buspirone. Neither is “better” for everyone; the doctor evaluates your situation. For another option, read the hydroxyzine guide.

SSRIs such as sertraline (Zoloft) and escitalopram (Lexapro) are antidepressants that are also used for several anxiety disorders. Buspirone is not an antidepressant. Both kinds are taken every day and take weeks to work, and their approved uses and side effects differ.

The label warns that taking buspirone with an SSRI or another medicine that raises serotonin increases the risk of serotonin syndrome; tell the doctor everything you take. None is “best” for everyone: the doctor chooses with you based on your symptoms, history and other medicines.