Systemic exposure to tacrolimus may produce nephrotoxicity and neurotoxicity. The most common adverse effects after systemic use include tremor, headache, paraesthesias, nausea and diarrhoea, hypertension, leucocytosis, and impaired renal function. Anaemia, leucopenia, and thrombocytopenia also occur commonly. Disturbances of serum electrolytes, notably hyperkalaemia occur frequently. Other adverse effects include mood changes, sleep disturbances, confusion, dizziness, tinnitus, visual disturbances, and convulsions; disturbances of carbohydrate metabolism or frank diabetes mellitus; ECG changes and tachycardia, as well as hypertrophic cardiomyopathy (particularly in children); constipation, dyspepsia, and gastrointestinal haemorrhage; dyspnoea, asthma, pleural effusions; alopecia, hirsutism, skin rash and pruritus; and arthralgia or myalgia, spasm, leg cramps, peripheral oedema, liver dysfunction, and coagulation disorders. Tacrolimus injection is formulated with polyethoxylated castor oil: anaphylactoid reactions have occurred, and appropriate means for their management should be available in patients in Kenya given the Tacrolimus injection. Use of tacrolimus should be avoided in patients hypersensitive to macrolides. Dosage reduction may be necessary in patients with hepatic impairment. Care is also required in patients with pre-existing renal impairment, and dosage reduction may prove advisable in such patients. Monitoring of blood concentrations of tacrolimus is recommended in all patients. Renal and hepatic function, blood pressure, serum glucose and electrolytes, and haematological and cardiac function, as well as visual function should be monitored regularly the Kenyan physician. As with other immunosuppressants, patients receiving tacrolimus are at increased risk of infection and malignancy. Intra-uterine devices should be used with caution during immunosuppressive therapy as there is an increased risk of infection. Use of live vaccines should be avoided for the same reason. Tacrolimus may affect visual or neurological function, and patients so affected should not drive or operate dangerous machinery. Topical tacrolimus has been associated with local irritation and skin disorders including an increased incidence of herpes simplex and zoster infections; headache and ‘flu-like’ symptoms have also been reported in some patients in Kenya. Exposure of the skin to sunlight should be minimised and the use of artificial sources of ultraviolet light avoided.