Terbinafine is an antifungal medication that comes in tablet form, as well as in creams and sprays, similar to Itraconazole 100mg Capsules. It’s used to treat a variety of fungal infections, from athlete’s foot to ringworm. This article will focus on the terbinafine 250 mg tablet, especially when taken twice daily.
When prescribed in this dose, terbinafine is typically used to treat onychomycosis (fungal nail infections) or other similar fungal infections.
If your doctor has prescribed terbinafine 250 mg twice daily, reading this article can help you understand more about how to take it, what to expect, and what side effects to watch out for. We’ll cover uses, dosages, drug interactions, adverse effects, warnings, and other key information.
What is terbinafine used to treat?
Terbinafine is an antifungal medicine that’s often prescribed to treat fungal infections. It comes in two forms: topical creams and oral tablets, much like Lamisil Cream. The tablets are a prescription medicine. The creams are available over the counter.
Terbinafine tablets are usually prescribed to treat:
- Onychomycosis (nail fungus)
Sometimes, doctors prescribe terbinafine tablets “off-label” to treat:
- Tinea pedis (athlete’s foot)
- Tinea corporis (ringworm)
- Tinea cruris (jock itch)
- Sporotrichosis
- Tinea capitis
Onychomycosis (nail fungus): The standard dose is 250 mg per day for 6 weeks if the infection is in your fingernails, and 12 weeks if it’s in your toenails. Your doctor will decide how long you’ll need to take the medicine, based on how well it’s working for you and how severe the infection is.
Tinea pedis (athlete’s foot), Tinea corporis (ringworm), and Tinea cruris (jock itch): You’ll probably take 250 mg once a day or 125 mg twice a day for 2 to 6 weeks. Your doctor will adjust the dose and duration of treatment based on how severe the infection is and how well you’re responding to the medicine.
Sporotrichosis: The usual dose is 500 mg per day, split into two doses, for 2 to 6 weeks. You’ll continue taking the medicine for an additional 2 to 4 weeks after the infection seems to have cleared. It can take 3 to 6 months for all the lesions to resolve.
Tinea capitis: The dose for tinea capitis in children depends on the child’s weight. Here are some general guidelines:
- Children 4 years and older, weighing less than 55 pounds: 125 mg per day for 6 weeks
- Children 4 years and older, weighing 55 to 77 pounds: 187.5 mg per day for 6 weeks
- Children 4 years and older, weighing more than 77 pounds: 250 mg per day for 6 weeks
Dosage and Administration
The typical adult dose of terbinafine is 250 mg twice daily, but your doctor will tell you the dose that’s right for you. It’s super important to follow your doctor’s instructions exactly when it comes to how much to take and for how long.
Even if you start feeling better, keep taking the medication for the full amount of time your doctor prescribed. If you stop early, the infection could come back.
Here are a few more things to keep in mind when taking terbinafine:
- You can take terbinafine with or without food.
- Taking the medication around the same time every day can help it work better.
- If you miss a dose, take it as soon as you remember. But, if it’s almost time for your next dose, just skip the missed one. Don’t take a double dose to make up for it.
How Terbinafine Works
Terbinafine works by blocking a specific process that fungi need to live. Because the cells in your body don’t have that process, terbinafine targets fungi without harming you.
How it works
Terbinafine stops fungi from making ergosterol, which is like the building block that makes up their cell membranes. Without ergosterol, the fungal cell dies.
How your body uses it
When you take terbinafine as a pill, your body absorbs it pretty well—usually, more than 70% of the medicine gets into your system. But, because of the way your liver processes it the first time around, only about 40% of that amount is actually available to fight the fungus.
If you take a 250 mg dose, the highest amount of terbinafine in your blood (about 1 microgram per milliliter) will be there in about 2 hours.
Once terbinafine is in your blood, it sticks to proteins. Your liver breaks down terbinafine with the help of several enzymes, and your kidneys remove about 70% of the drug from your body. It takes a long time for your body to get rid of terbinafine completely—between 200 and 400 hours.
Who should not take terbinafine?
Terbinafine is a powerful medicine, and it isn’t right for everyone. Before taking terbinafine, be sure to discuss your health history with your healthcare provider.
Contraindications
Do not take terbinafine if you:
- Have kidney problems, especially if your creatinine clearance (CrCl) is less than 50 mL/min.
- Have ongoing or chronic liver disease.
- Have had an allergic reaction to terbinafine or any of the inactive ingredients in the medication.
Terbinafine can be hard on your kidneys and liver, so it’s not safe to take if these organs aren’t functioning well.
Warnings and precautions
Tell your doctor if you:
- Experience liver problems: Your doctor should check your liver function regularly while you’re taking terbinafine.
- Have skin reactions: Stop taking terbinafine right away and tell your doctor if you develop a severe skin rash or other unusual symptoms.
- Have blood disorders, lupus, or a weakened immune system: These conditions can increase your risk of side effects from terbinafine.
- Have an autoimmune condition: Terbinafine may make autoimmune conditions worse.
Finally, be aware that caffeine can sometimes interact with terbinafine. Talk with your doctor about whether you need to reduce or eliminate caffeine from your diet during treatment.
Drug Interactions
Drug interactions are a concern with any medication, including terbinafine. When you take more than one drug, the ways they interact can sometimes cause side effects or make a drug less effective.
CYP450 Enzyme Interactions
Terbinafine is processed by the body using CYP450 enzymes, which means that there’s a chance for interactions with other drugs that use the same enzymes. Drugs that either speed up or slow down these enzymes can change the amount of terbinafine in your blood.
Specific Drug Interactions
Some specific drugs are known to interact with terbinafine:
- Metoclopramide intranasal, pacritinib, and Saccharomyces boulardii: You may need to adjust the dose of terbinafine or switch to a different medication.
- Warfarin: Terbinafine may change how well warfarin works to prevent blood clots. If you take these drugs together, your doctor will need to keep a close eye on your INR (international normalized ratio).
- Amphetamine: Terbinafine can interact with amphetamine.
- Other medications: Be aware that terbinafine might interact with other drugs that are processed by CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19.
Managing Drug Interactions
Before you start taking terbinafine, here’s what you should do:
- Make a list of all the medications you take. Include prescription drugs, over-the-counter medications, and any herbal supplements.
- Talk to your doctor or pharmacist. They can help you check for potential drug interactions.
- Keep an eye on how the drugs affect you. If you notice any changes, let your doctor know.
It’s always a good idea to be proactive about drug interactions. The more information you share with your healthcare provider, the better they can help you stay safe and healthy.
What are the side effects of terbinafine?
Like all medications, terbinafine can cause side effects. Some are more common than others, and some can be serious. If you experience any unusual or severe symptoms while taking terbinafine, contact your healthcare provider right away.
Common side effects (more than 10% of users)
- Headache (experienced by 13% of users in studies)
- Abnormalities in liver function tests
Less common side effects (1-10% of users)
- Rash (6%)
- Itching (3%)
- Nausea (3%)
- Diarrhea (6%)
- Indigestion (4%)
Rare and serious side effects
These side effects are rare, but they require immediate medical attention:
- Severe skin reactions, such as Stevens-Johnson Syndrome or toxic epidermal necrolysis
- Blood disorders, such as neutropenia or thrombocytopenia
- Anaphylaxis (a severe allergic reaction)
- Liver failure
Side effects reported after the drug was released to the market
These side effects have been reported since terbinafine became available:
- Agranulocytosis (a dangerously low white blood cell count)
- Pancytopenia (a deficiency of all blood cell types)
- Allergic reactions, including hives and angioedema (swelling under the skin)
Monitoring and reporting
It is important to tell your doctor right away if you have any unusual or severe symptoms. Your doctor may want to monitor your liver function and blood cell counts during terbinafine treatment.
Terbinafine use in specific populations
If you are pregnant, breastfeeding, or caring for a young child or an elderly relative, here are some special things to keep in mind about terbinafine.
Pregnancy
If you’re pregnant, you shouldn’t take terbinafine unless the benefits of taking it are much greater than the risks. Researchers don’t know a lot about the risks of terbinafine during pregnancy. Animal studies have shown that there could be risks.
Lactation
Terbinafine does get into breast milk. If you’re breastfeeding, you and your doctor should think about the benefits of breastfeeding along with the risks of taking terbinafine. You’ll need to weigh the risks and benefits carefully.
Children and older adults
Researchers don’t have a lot of information about how safe and effective some forms of terbinafine are for children under 4 years of age and for older adults. If you are elderly, your doctor may want to change your dose because of age-related changes in how well your kidneys and liver work.
Frequently Asked Questions
Is weight gain a side effect of terbinafine?
Weight gain isn’t a commonly reported side effect of terbinafine. However, everyone reacts differently to medications. If you experience unexplained weight gain while taking terbinafine, it’s best to consult your doctor to rule out other potential causes.
What kills toenail fungus permanently?
There’s no guaranteed “permanent” cure for toenail fungus, as reinfection is always possible. However, oral antifungal medications like terbinafine are often the most effective treatment option. Consistent use as prescribed, combined with good foot hygiene, provides the best chance of clearing the infection and preventing recurrence.
Can I take terbinafine 250 mg twice a day?
Terbinafine is typically prescribed at a dose of 250 mg once daily for toenail fungus. Taking 250 mg twice a day would be considered an off-label use and should only be done under the direct supervision and guidance of a qualified healthcare professional. Never adjust your dosage without consulting your doctor.
Is 250mg of terbinafine a lot?
250 mg is the standard daily dose of terbinafine for adults being treated for fungal infections like onychomycosis (toenail fungus). Whether or not it’s “a lot” depends on the individual, their condition, and other medications they may be taking. Always follow your doctor’s prescribed dosage instructions.
Do I need to throw away my shoes if I have toenail fungus?
While you don’t necessarily need to throw away your shoes, it’s a good idea to disinfect them regularly. Fungus can thrive in shoes, leading to reinfection. Consider using an antifungal spray inside your shoes to help eliminate fungal spores. Also, alternate shoes to allow them to dry thoroughly between wearings.
In Closing
Terbinafine 250 mg twice daily is a strong medication that can treat fungal infections like onychomycosis (toenail fungus). However, it can interact with other medications and cause side effects. Because of this, it’s important to follow your doctor’s instructions carefully and to tell them about any changes in your health.
Careful monitoring and management of side effects can help ensure that terbinafine is used safely and effectively.