Does buspirone (Buspar) increase appetite?

Does Buspar Increase Appetite?

Yes, buspirone (Buspar) can increase appetite as a documented adverse effect, though this is not its primary therapeutic action.

Evidence from FDA Drug Label

According to the official FDA prescribing information, increased appetite is listed as one of the most common adverse effects of buspirone 1. The drug label specifically identifies "increased appetite" among the frequent side effects observed in clinical trials, particularly in the buspirone treatment group 2.

Clinical Context and Mechanism

Buspirone works primarily as a serotonin 5-HT1A receptor agonist with moderate affinity for dopamine D2 receptors 1. While its mechanism for appetite stimulation is not fully elucidated in the FDA label, the serotonergic activity likely plays a role in modulating feeding behavior.

Supporting Research Evidence

• In autism treatment: A randomized controlled trial demonstrated that buspirone plus risperidone resulted in increased appetite as one of the most common adverse effects (81.2% of patients showed clinical improvement, though increased appetite was noted as a side effect) 2

• Animal studies: Multiple preclinical studies confirm buspirone's appetite-stimulating properties:

  • Buspirone increased carbohydrate intake specifically in rats, regardless of nutritional status or route of administration 3
  • Enhanced feeding duration was observed in novel environments, though directed primarily toward familiar foods 4

Important Clinical Considerations

This appetite increase should NOT be confused with therapeutic appetite stimulation used in cancer cachexia or wasting syndromes. The cancer cachexia guidelines do not recommend buspirone as an appetite stimulant for that indication 5, 6. The guidelines specifically endorse megestrol acetate and corticosteroids for therapeutic appetite stimulation in cancer patients, not buspirone.

Key Distinctions:

• Buspirone's appetite increase = adverse effect during anxiety treatment
• Therapeutic appetite stimulants (megestrol acetate, corticosteroids) = intentional treatment for cachexia

Practical Implications

When prescribing buspirone for anxiety:

• Counsel patients that increased appetite may occur as a side effect
• Monitor weight during treatment, especially in patients concerned about weight gain
• The effect appears dose-related and occurs commonly enough to warrant discussion during informed consent
• This side effect is generally mild to moderate and did not cause treatment discontinuation in most clinical trials 1

The appetite increase with buspirone is a recognized adverse effect that clinicians should anticipate and discuss with patients, though it remains secondary to the drug's primary anxiolytic indication.