There are five main categories of drugs that are prohibited from sports:

Anabolic steroids - these help athletes build muscle, and to recover faster from training.

Peptide hormones - these are substances that occur naturally in the body. They produce similar effects to anabolic steroids.

Beta-2 Agonists - these relax the smooth muscle that surrounds the lungs permitting more air to enter the lungs.

Stimulants - these raise the heart rate and may improve performance.

Diuretics - these help the body to lose fluids and are often used to mask the presence of other drugs.

In addition to the five main performance enhancing drugs classes above, local anaesthetics, cortico-steroids used to treat medical conditions such as asthma, and beta-blockers used to treat heart conditions, are subject to restrictions on their use.

Anabolic steroids are the most common performance enhancing drug in sport.

Anabolic steroids are drugs related to the male sex hormone testosterone. The word 'Anabolic' refers to muscle building and 'steroids' refers to the class of drugs.

Anabolic steroids were developed in the late 1930s with the main aim of treating a medical condition in men where the testes do not produce sufficient testosterone for normal growth, development and sexual functioning -hypogonadism. Medical uses of steroids include the treatment of delayed puberty, some types of impotence, and wasting of the body caused by HIV infection or other diseases.

During the 1930s, scientists discovered that anabolic steroids could facilitate the growth of skeletal muscle in laboratory animals, which led to use of the compounds first by bodybuilders and weightlifters and then by other athletes.

More than 100 different anabolic steroids have been developed, but they require a prescription to be used legally in most countries.

To check whether a medication or supplement contains a Prohibited Substance, complete the Product Information Request form on the Tennis Anti-Doping app, free to download onto Android (Google play) and Apple (App Store) devices.  Requests for information on pharmaceutical products are processed 7 days a week during office hours, and are  normally returned within 24 hours, unless the request is for a large number of products and/or ingredients, in which case processing may take up to 72 hours or more in exceptional circumstances.