Nystatin

What it is

Nystatin is a polyene antifungal. It binds sterols in the fungal cell membrane and opens pores in it, so the cell leaks and dies. It is used for fungal infections on surfaces the drug can reach directly, such as thrush in the mouth and gut.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Fungal infection

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

Very little of it is absorbed from the gut, so it works where it touches and does not carry the drug interactions of the swallowed antifungals. Contact time is what matters: where an oral liquid is marketed — Japan's PMDA now lists no nystatin product at all — it is kept in the mouth as long as comfortably possible before swallowing, and eating or drinking straight afterwards washes it away. It can be taken with or without food, and mild nausea or a loose stomach are the usual complaints.

When to see a doctor

See a doctor if the infection does not improve over the course, returns quickly or keeps coming back, or if a rash, swelling of the mouth or face, or trouble breathing appears.