Cycling has introduced EPO testing

How and when used: Cyclists drug of choice. Injected under the skin.
Aims: Stimulates red blood cell production to allow blood to carry more oxygen and gives a particular advantage to endurance athletes like cyclists.
Serious side effects: Can thicken the blood leading to the risk of blood clots, heart attacks and strokes.

Corticosteroids (restricted/banned in tablet or syrup form)

How and when used: Richard Virenque tested positive for these in the 1998 Tour. Asthma medications, hay fever preparations and creams/ointments for inflammatory skin disorders. Also injected to treat inflammation of tissues.
Aims: Anti-inflammatory and to create feeling of euphoria.
Serious side effects: Osteoprosis, increased blood pressure.

Stimulants (banned/caffeine is prohibited in large quantities)

How and when used: Includes ephedrine and can be contained in over-the-counter cold and hay fever remedies.
Aims: Reduce weight, increase competitiveness, combat fatigue.
Serious side effects: Irregular heart beat, can lead to cardiac arrest and strokes.

Blood boosting

How and when used: Blood is taken from athlete and frozen and stored for six to eight weeks. The athlete's blood rebuilds itself over the next weeks. Just before competition, the stored blood is given back to the athlete.
Blood can also be injected from another person or synthetic blood products can also be used. Raids at the Giro d'Italia are reported to have uncovered Hemassist, a blood substitute
Aims: Replicates effect of EPO: Increases aerobic performance by bosting oxygen carrying capacity of blood.
Serious side effects: Thickens blood raising risk of clots, risk of infection.