The commonest side-effects that occur in patients receiving FTC (emtricitabine, Emtriva) are headache, diarrhoea, nausea, and rash. In clinical trials, these have generally been of mild to moderate severity.

Skin discoloration is the only side-effect which was more common among people taking FTC compared with other antiretrovirals in clinical trials. Excess pigmentation on the palms or soles of the feet was predominantly observed in non-Caucasian patients, although it was mild and did not result in treatment discontinuation^[1]. The mechanism and clinical significance of this side-effect are unknown.

Abnormal kidney function has been reported in two people receiving the 200mg dosage of FTC.

As with other nucleoside reverse transcriptase inhibitors (NRTIs), FTC may cause elevations of lactic acid in the blood. One study has shown that this only occurs when FTC is used with d4T (stavudine, Zerit)^[2]. The commonest symptoms of lactic acidosis are:

• Lethargy.
• Unusual muscle pain.
• Difficulty breathing.
• Stomach pain with nausea and vomiting.
• Feeling cold, especially in the arms and legs.
• Dizziness or light-headedness.
• A fast or irregular heartbeat.

Serious liver damage, characterised by liver enlargement and a build-up of fat in the liver are also potential side-effects of FTC. These are characterised by:

• Jaundice (yellowing of the skin and whites of the eyes).
• Dark urine.
• Light coloured stools.
• Lack of appetite.
• Nausea.
• Stomach pains.

Patients experiencing the symptoms of lactic acidosis or liver toxicity should contact their doctor immediately.

Long-term use of FTC does not seem to produce the fat wasting seen among patients treated with d4T, and produces only moderate elevations in triglycerides. However, the incidence of laboratory abnormalities, such as elevated liver enzyme or cholesterol levels, is similar in patients treated with FTC and those treated with 3TC (lamivudine, Epivir) or d4T^[3].