What are worms?

Worms (sometimes called helminths) are parasites that enter the body and are able to live and feed off the person they have entered. There are many types of worms and they are usually divided into three groups:

Roundworms - the most common roundworm infections are thought to be caused by threadworms, ascaris, hookworms and trichuris. Roundworm eggs usually enter the body by the person eating food or drinking water that contains eggs. The eggs live and hatch in the gut (intestine).
Tapeworms - these worms live in the gut. People usually become infected by eating raw or uncooked meat.
Flukeworms - these worms can live in the blood vessels, gut, lungs or liver. You usually become infected with flukeworms by swimming or washing in fresh water that contains flukeworms. An infection with flukeworms causes a tropical disease called schistosomiasis.

Most worm infections occur in warm tropical countries or developing countries where food and water may not be clean. It is thought that millions of people around the world are infected with worms at any one time. In the UK the most common worm infection is threadworms - this is a type of roundworm and is sometimes referred to as a pinworm. Threadworms are spread by being in contact with someone who is already infected with threadworms. Threadworms can cause an itchy bottom.

Which medicines are usually prescribed for worms?

There are several medicines that may be used to treat worm infections - they are sometimes called anthelmintics. Mebendazole is the most commonly prescribed medicine for worms in the UK. This is because it is used to treat threadworms which are the most common worm infections in the UK. Mebendazole is also used to treat roundworm, whipworm and hookworm infections.

Other medicines that may be prescribed for the various types of worm infections include:

Levamisole
Niclosamide
Praziquantel
Albendazole
Diethylcarbamazine
Ivermectin
Tiabendazole

These medicines are not licensed for use in the UK and are specially imported to treat more unusual worm infections. They are usually prescribed by doctors who specialise in treating worm infections.

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