Active Ingredients

Terbinafine – Effect, Application & Risks


The active ingredient terbinafine is used to treat fungal diseases . The remedy can be used both locally and systemically.

What is terbinafine?

Terbinafine is an allylamine derivative that is one of the antifungals . The antifungal agent is mainly used to treat athlete’s foot (tinea pedis) and nail fungus (onychomycosis). It is suitable for local (topical) treatment in the form of creams, but can also be used systemically with tablets. Because of its chemical structure, terbinafine belongs to the group of allylamines.

Terbinafine was developed by the Swiss pharmaceutical company Novartis. From 1991, the antimycotic came onto the market in Europe. The USA joined in 1996. In Germany, several generics containing terbinafine can now also be administered.

Pharmacological action

Fungi , which can cause disease in humans, are composed of individual cells. A cell is the smallest independent unit in all life forms. For the targeted treatment of fungal diseases, medicine uses the differences between the various forms of life in order to effectively combat the fungal cells in this way. However, since the cell differences to humans are not always very pronounced, numerous antimycotics are directed against the cell membrane. This has a different structure in fungi and humans.

The membrane of humans and animals is composed primarily of lipids such as cholesterol . Cholesterol gives the human cell membrane flexibility, allowing it to withstand environmental influences. In fungi, this function is performed by ergosterol, a substance chemically similar to cholesterol. However, there are some crucial differences in structure.

The effect of ergosterol can be slowed down by terbinafine. The drug inhibits the important enzyme squalene epoxidase, which counteracts the build-up of the fungal cell wall. In addition, the starting material squalene accumulates within the fungal tissue. As a result, most of the mushrooms will die.

Terbinafine unfolds its fungicidal effect even in low concentrations on moulds , skin fungi and some dimorphic fungi. Yeasts are also prevented from growing or killed by the antifungal, depending on the type of yeast fungus.

The duration of action of terbinafine is considered to be long-lasting. The absorption of the substance in the intestine is assessed as good. However, parts of the active substance are rapidly broken down in the liver . As a result, only 50 percent of the dose gets into the bloodstream . After about 90 minutes, terbinafine has reached its highest level there. Due to its fat solubility, the antifungal agent can easily reach the skin and nails. About 30 hours after taking it, about 50 percent of the terbinafine has left the body. The degradation products are excreted via urine and stool .

Medical Application & Use

The most important areas of application of terbinafine are skin fungal infections caused by dermatophytes such as athlete’s foot or nail fungus. Furthermore, the antimycotic can be administered against candidiasis (yeast infections), bran lichen and against the fungus Microsporum canis. This is common in the animal kingdom. It is not uncommon for it to be transmitted from cats to children.

In addition to its external administration, terbinafine is used internally in the form of tablets in the case of onychomycosis (fungal infections of toenails and fingernails). External administration of terbinafine takes the form of gels, sprays or one-percent creams. These are applied to the body parts to be treated once or twice a day. Depending on the type of fungal infection, the duration of therapy is one to two weeks.

Internal administration through tablets containing 250 milligrams of terbinafine occurs when the patient suffers from severe nail or skin fungal infections. The tablets are taken once a day with a glass of water, regardless of meals. It is recommended to always take the tablets at the same time of the day.

The duration of terbinafine use depends on the severity of the disease. While it usually takes four to six weeks for skin fungal infections, it can last up to three months for nail fungus.

Risks & side effects

Around ten percent of all patients suffer from undesirable side effects during therapy with terbinafine . The nature of the side effects depends on the form of dosage. Local application can lead to allergic reactions in the treated areas of skin ( redness , itching or burning ). In individual cases, the allergy spreads to the affected regions and leads to widespread reactions.

When used internally, side effects such as loss of appetite , feeling of fullness , nausea , vomiting , diarrhea , slight abdominal pain , joint pain , muscle pain , rashes on the skin, hives , headaches and taste disorders are possible.

If allergic reactions or skin irritation develop during terbinafine therapy, treatment should be discontinued. If a sore throat or high fever occurs , a doctor must be consulted immediately.

Terbinafine should not be administered internally or externally if the patient is hypersensitive to the drug. In the case of acute or chronic liver disease or alcohol addiction , terbinafine cannot be administered in tablet form. The same applies to significant limitations in kidney function .

Few data are available on use during pregnancy . For this reason, the administration of the antifungal agent should only take place after medical advice. Because terbinafine passes into breast milk , its internal and external use should be avoided during breastfeeding .

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.