Months: terbinafine tablets typically run up to 3 months, and the NHS says some nail infections take 6 months or longer - because the drug clears the fungus long before the damaged nail can grow out.
The ugly nail is dead keratin; it only looks normal as clean nail grows from the base, and a big toenail takes about a year to replace. Judge by the clear band at the cuticle, not the tip. Rules: take the full course (stopping early because it looks unchanged is the classic failure); big-toe infections clear slowest; expect liver-function checks on long courses - report dark urine, pale stools, or yellowing skin promptly. Treat any athlete's foot at the same time, or it reinfects the nail. Pymander is a free AI doctor, 24/7 by text, and can help you judge your progress.
What to do
Common questions
How long does terbinafine take to cure toenail fungus?
Toenail fungus is a marathon. The NHS sets the timeline honestly: terbinafine tablets may be taken for up to 3 months (sometimes longer), and some fungal nail infections take 6 months or longer to get better. The reason is biology: the medicine clears the fungus within weeks to months, but the thick, discolored nail you see is dead keratin - it only looks healthy again as new, clean nail grows out from the base, and a big toenail takes about a year to fully replace itself. So judge the treatment by the clear band of new nail at the cuticle, not by the ugly tip, which has to grow off. The practical rules: take the tablet daily for the full prescribed course - stopping early because it looks unchanged is the classic failure; infections on the big toe clear more slowly, and younger people clear faster, per the NHS; and your doctor may check liver function before and during a long course, because terbinafine tablets carry a small liver risk - report dark urine, pale stools, nausea, or yellowing skin promptly. Cream versions exist but cannot penetrate a nail plate - they are for skin infections like athlete's foot, which often ride along with the nail infection and should be treated simultaneously to prevent reinfection. Pymander is a free AI doctor, 24/7 by text, that can help you judge whether your nail is on schedule.