Terbinafine is used to treat fungal infections of the toenail and fingernail. Terbinafine is in a class of medications called antifungals. It works by stopping the growth of fungi.

Terbinafine comes as a tablet to take by mouth. It is usually taken once a day for 6 weeks for fingernail fungus and once a day for 12 weeks for toenail fungus. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take terbinafine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your fungus may not be completely cured until a few months after you finish taking terbinafine. This is because it takes time for a healthy nail to grow in.

Cream: Apply enough cream to cover the affected areas, and do not cover with any kind of drressing unless directed by your doctor to do so. Wash hands thoroughly before and after each application.

Terbinafine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

diarrhea
upset stomach
stomach pain
rash
itching
hives
changes in taste or loss of taste
Some side effects can be serious. The following symptoms are uncommon, but if you experience any of them, call your doctor immediately:

upset stomach that does not go away
loss of appetite
extreme tiredness
vomiting
pain in the right upper part of the stomach
dark urine
pale stools
severe skin rash that keeps getting worse
fever, sore throat, and other signs of infection
Terbinafine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body response to terbinafine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

Before taking terbinafine,

tell your doctor and pharmacist if you are allergic to terbinafine or any other medications.
tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking. Be sure to mention any of the following: anticoagulants (blood thinners) such as warfarin (Coumadin); antidepressants such as amitriptyline (Elavil), amoxapine (Asendin), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Adapin, Sinequan), imipramine (Tofranil), nortriptyline (Aventyl, Pamelor), protriptyline (Vivactil), and trimipramine (Surmontil); beta-blockers such as atenolol (Tenormin), labetalol (Normodyne), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), and propranolol (Inderal); cimetidine (Tagamet); medications that suppress the immune system such as azathioprine (Imuran), cyclosporine (Neoral, Sandimmune), methotrexate (Rheumatrex), sirolimus (Rapamune), and tacrolimus (Prograf); rifampin (Rifadin, Rimactane); and selegiline (Eldepryl). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
tell your doctor if you have or have ever had kidney or liver disease, human immunodeficiency virus (HIV), or acquired immunodeficiency syndrome (AIDS).
tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking terbinafine, call your doctor. You should not take terbinafine while breast-feeding.