Terbinafine Dosages for Adults: Your GoodRx Guide

Nail fungus can be unsightly and difficult to treat. If your healthcare provider has recommended taking a pill to help, you’ve likely been prescribed terbinafine. Oral terbinafine is one of the most effective treatments for nail fungus, but taking it correctly is important. Here, you’ll find everything you need to know about typical terbinafine dosages for adults.

Good to know: Terbinafine tablets aren’t FDA approved for children, which is why you’ll only find adult dosages in this article. If your child has nail fungus, talk to their healthcare provider about safe treatment options. Some providers may still prescribe oral terbinafine off-label. But children’s nails are thinner and grow faster. So compared to adults, kids are more likely to have good results with topical nail fungus treatments (those applied to the skin and nails).

What’s the typical terbinafine dosage for adults?

Patience is key when it comes to taking terbinafine. You’ll need to take your dose every day for many weeks. And it can still take up to 12 months (1 year) after your last dose before your nail(s) appear better. It takes time for healthy nails to grow out after terbinafine has treated your infection.

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Fingernail fungus

The terbinafine dosage for fingernail fungus is one tablet (250 mg) by mouth once daily for 6 weeks. You can take terbinafine with or without food. Taking it with food may help lessen or prevent stomach upset.

Toenail fungus

The terbinafine dosage for toenail fungus is one tablet (250 mg) by mouth once daily for 12 weeks. You can take terbinafine with or without food. Taking it with food may help lessen or prevent stomach upset.

Are there any dosage adjustments for health conditions?

Terbinafine doesn’t have specific dosage adjustments for health conditions. But terbinafine might interact with other medications you’re taking. In those cases, your healthcare provider may adjust the dosage of one or more of your medications. Make sure you share an updated medication list with your provider and pharmacist before starting terbinafine.

There are some cases, though, where terbinafine should be avoided altogether. Your provider will likely choose a different treatment option if one of these situations applies to you.

Lupus

Your provider may be cautious about prescribing terbinafine tablets if you have active lupus. There are reports of terbinafine tablets worsening symptoms for people who have lupus. But this complication is rare.

Depending on your personal risk factors, your provider may choose to prescribe this antifungal and monitor you closely for lupus symptoms. But they may also just choose a different treatment to help avoid this potential issue.

Pregnant or nursing women

Terbinafine tablets generally aren’t recommended during pregnancy. Some studies suggest the medication may be safe. But more studies are needed to confirm this. Discuss your options with your healthcare provider.

Terbinafine also isn’t usually recommended if you’re nursing. We know that terbinafine makes its way into breastmilk. But there isn’t much data to know if this is harmful to breastfed infants.

Since nail fungus isn’t typically a dangerous condition, some providers may recommend waiting until you’re no longer pregnant or nursing to treat it. You can also ask your provider about topical treatment options. Many of these are considered safer during pregnancy or while breastfeeding.

If you become pregnant while taking terbinafine, contact your provider. They can guide you on next steps to take.

Liver problems

Before starting terbinafine, your provider will likely ask you to go for a blood test to check your liver health. Terbinafine has a rare, but serious, side effect of liver damage.

Liver tests usually return to normal within 3 to 6 months after stopping terbinafine. Still, cases of persistent liver damage have occurred — but this is very rare. It’s more likely to happen in people who already have liver problems.

Because of this risk, you shouldn’t take terbinafine if you have any issues with your liver. Even with a healthy liver, your provider will monitor blood tests during treatment to screen for problems.

You can protect your liver while taking terbinafine by keeping an eye out for signs of liver problems. Get medical help if you develop any of these symptoms of liver damage:

• Nausea

• Loss of appetite

• Tiredness

• Pale stools

• Dark urine

• Pain in the right upper part of your stomach

• Yellowing of the skin or eyes (jaundice)

What happens if you miss a dose of terbinafine?

If you miss a dose of terbinafine, take the missed dose as soon as you remember. But if your next dose is in less than 4 hours, skip the missed dose. Then continue your regular dosing schedule. Don’t take extra medication to make up for a missed dose.

What happens if you stop terbinafine too soon?

It’s important to finish the full course of your terbinafine prescription. Stopping too soon may make your infection come back. The infection may also be harder to treat.

Remember that it takes several months to see results with terbinafine. Check in with your healthcare provider if you feel like terbinafine isn’t working. It may just be a case of needing more time.

What should you do if you take too much terbinafine?

Taking an extra dose by mistake is unlikely to cause serious harm. But you may experience more side effects than usual. Common side effects include headache, diarrhea, and indigestion.

Be sure to stick to the instructions your healthcare provider has given you. Taking more terbinafine won’t speed up results, and it can put you at risk for dangerous side effects.

Taking terbinafine too often, or taking an excessive amount at once, can be harmful. Contact your healthcare provider if you’ve taken more terbinafine than you’re supposed to. They may do a lab test to check that your liver is OK. Even if you feel fine, still check in. You may not feel symptoms even if your liver has been damaged. You can also call Poison Control at 1-800-222-1222 for guidance.

How to save on terbinafine

There are many ways to save on terbinafine, which is available as a generic medication. GoodRx can help you save over 70% off the average retail price. The price of 30 terbinafine tablets at certain pharmacies is as low as $12.34 with a free GoodRx discount.

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Written by:

Tegan Smedley, PharmD, APh

Tegan Smedley, PharmD, APh, has 10 years of experience as a pharmacist. She has worked in a variety of settings, including retail, hospital, and ambulatory care.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Daphne Berryhill, RPh

Daphne Berryhill, RPh, has two decades of experience as a clinical pharmacist. She spent most of her career in the Chicago area practicing in-home infusion.

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