Active Ingredients

Terfenadine – Effect, Application & Risks


Terfenadine is an antiallergic drug and is used to treat allergic reactions . Since it competes for the histamine receptor site in the human organism, the body’s own hormone histamine can no longer dock. Histamine is responsible for allergic symptoms such as itching and redness . Terfenadine is administered in tablet form. It has been withdrawn from the market in some countries because it has caused cardiac arrhythmias in some patients. There are also other side effects of the drug.

What is terfenadine?

Terfenadine is an antihistamine . It is used to treat allergies . It was first manufactured in the 1970s and launched in 1982. The active ingredient was available without a prescription for a very long time. Terfenadin is marketed in Germany under the drug names Hisfedin®, Terfemundin® and Terfedura®.

Terfenadine is a so-called racemate. A racemate is a drug composed of two molecules in a one-to-one ratio that exhibits pharmacological activity. The active ingredient is in the form of a crystalline, white powder and is very poorly soluble in water.

Terfenadine is a prodrug. Prodrugs are active ingredients that initially have no pharmacological effect. They only develop their effect through a conversion step in the human body. The pharmacologically active conversion form is called fexofenadine . This substance belongs to the second generation of antihistamines.

Terfenadine has been withdrawn from the market in many countries due to its potentially life-threatening side effects. Fexofenadine itself is approved as a possible alternative for the treatment of allergic symptoms.

Pharmacological action

Terfenadine has an antiallergic and antihistamine effect. Accordingly, the drug is used in human medicine to treat allergic reactions. Antihistamines are active ingredients that inhibit the body’s own hormone histamine. They have an anti-inflammatory and anti-itching effect. These medicines can also have a calming and sleep-inducing effect.

Terfenadine competes for the histamine-binding receptor in the bronchial muscles, uterus and digestive tract . This docking point for the body’s own neurotransmitter is also called the H1 receptor. The histamine can no longer bind to the receptor due to the terfenadine and cannot develop its effect. This reduces the symptoms of an allergy caused by histamine. Itching, redness and edema formation decrease.

Medical Application & Use

In Germany, the active ingredient terfenadine is approved for the treatment of allergic conjunctivitis and allergic rhinitis. Allergic rhinitis is also known as hay fever . Conjunctivitis is inflammation of the conjunctiva of the eye. In addition, allergic skin reactions, such as hives , can be treated with the drug.

Terfenadine must not be administered in the case of pre-existing heart conditions , impaired liver function , anorexia , vomiting , diarrhea and disorders of the magnesium or potassium balance. Treatment with concomitant therapy with other drugs such as antibiotics or antifungals is also a contraindication for this drug.

If the patient is taking drugs to treat cardiac arrhythmia, terfenadine should not be prescribed. In addition, pregnant women and children should not take the active ingredient. People weighing less than 50 kilograms should not be treated with the substance.

Terfenadine should be taken as directed by your doctor. Depending on the degree of symptoms, one to two tablets are usually prescribed per day. The tablets should be administered with plenty of liquid and not chewed. Terfenadine should not be taken with grapefruit juice. This drink can immensely delay the breakdown of the substance in the body. Storage of the drug should be out of the reach of children.

Risks & side effects

The drug is usually well tolerated. However, side effects such as insomnia , fatigue , dizziness , lightheadedness , gastrointestinal upset , depression , or muscle tremors may occur.

In many countries, such as Switzerland, terfenadine has been withdrawn from the market because, in some cases, serious cardiac arrhythmia has occurred after ingestion. These can cause ventricular fibrillation and ultimately be fatal. Symptoms such as loss of consciousness , cramps , dizziness, low blood pressure or heartbeats that can be felt can indicate these cardiac arrhythmias. Due to this fact, special care should be taken when taking the drug.

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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.