Side effects: include anaemia, nausea and vomiting, loss of appetite, abdominal pain, indigestion, headache, rash, fever, aching muscles, pigmentation of the skin, nails, and mouth, and reduced production of white blood cells.

Precautions: zidovudine should not be given to people with severe anaemia or a very low white-blood-cell count; blood tests may be required during the first three months of treatment. It should be used with caution in those with kidney or liver disease and in pregnant women; breastfeeding is not recommended during treatment.

Interactions with other drugs:
Aciclovir: causes extreme lethargy.
Clarithromycin: reduces the absorption of zidovudine,
Gancidovir: greatly reduces production of blood cells in the bone marrow.
Methadone: increases the plasma concentration (and therefore side effects) of zidovudine.
Fhenytoin: the plasma concentration of phenytoin is altered.
Frobenecid: increases the plasma concentration of zidovudine.
Proprietary preparations: Retrovir; COMBIVIR (combined with lamivudine).