Buspirone and fluconazole: raised buspirone levels and dose caution

The NHS describes fluconazole as an antifungal medicine used to treat infections caused by different kinds of fungus, most commonly candida. It is used for thrush in men and women, including vaginal thrush, balanitis and oral thrush, and for infections elsewhere in the body, and it can be used to prevent fungal infection in people who are at particular risk.

It is available on prescription, and the NHS adds that it can also be bought from a pharmacy for vaginal thrush or balanitis. For thrush, fluconazole capsules are also sold with clotrimazole cream. That is relevant because a purchase over the counter relies on the pharmacist asking about other medicines.

The NHS says the infection usually improves within 7 days for vaginal thrush, balanitis or oral thrush. The sources read do not give a figure for how long the effect on buspirone lasts.

The BNF interaction list for buspirone states that fluconazole is predicted to increase the exposure to buspirone. The manufacturer advises use with caution and to adjust the dose. The severity is moderate and the evidence type is study. The fluconazole list carries the same entry.

Exposure to a medicine is the amount present in the body. If it is higher than planned, effects and side effects of the medicine can be stronger. The sources read for this guide do not describe buspirone's side effects or its uses, so this page does not list them. The patient information leaflet, or the prescriber, can explain what to watch for with your own medicine.

The BNF buspirone list shows that fluconazole is one of several medicines in the same pattern. Other azole antifungals are rated higher: itraconazole, ketoconazole, posaconazole and voriconazole are each predicted to increase exposure with advice to adjust the buspirone dose and a severe rating. Isavuconazole and miconazole follow the fluconazole wording of use with caution.

Some antibiotics and heart medicines appear too. Clarithromycin is rated severe with advice to adjust the buspirone dose. Erythromycin, diltiazem and verapamil are predicted to increase exposure with advice to use caution and adjust dose. In the opposite direction, carbamazepine and rifampicin are predicted to decrease exposure.

If you take buspirone and have symptoms of thrush, ask the pharmacist before buying fluconazole, and say which medicines you take. The pharmacist can advise whether to use it, to use a topical alternative, or to see a GP. The NHS fluconazole interactions page lists a long set of medicines to discuss with a doctor, including pimozide, quetiapine, amisulpride, haloperidol, lithium, risperidone, escitalopram, venlafaxine, erythromycin, clarithromycin, warfarin, clopidogrel, carbamazepine, losartan and statins. Buspirone is not named in that list, which the NHS says is not complete, so the BNF is the reference for this pair.

If a GP prescribes fluconazole for a longer course, mention buspirone at the time. Do not change the buspirone dose yourself in either direction.

There is no specific symptom list for this pair in the sources read. As general advice, if you feel unusually drowsy, dizzy or unwell after adding a medicine, contact your pharmacist, GP or NHS 111, and call 999 for collapse or difficulty breathing. Take the medicine packets with you if you are seen in person.