Complications of post transplant treatment

Calcineurin inhibitors:
- Dose related nephrotoxicity
- Tremors
- High blood pressure (hypertension)

Corticosteroids
- Easy bruising of the skin
- Osteoporosis
- Avascular necrosis (bone death)
- High blood pressure (hypertension)
- High blood sugar because of glucose intolerance (increased risk of post transplant diabetes)
- Stomach ulcers
- Weight gain
- Acne
- Mood swings
- Round face
- Growth retardation
- Lipid abnormalities (hyperlipidemia)
-
Azathioprine
- Suppression of bone marrow
- Liver damage

Sirolimus
- Reduced wound healing
- Myelosuppression

Mycophenolic acid
- Nausea and diarrhoea

As post transplant treatment basically suppresses the immune system, the host is generally more susceptible to opportunistic infections by pathogens such as cytomegalovirus, fungi, Legionella species.

References:
http://www.emedicine.com/med/topic3406.htm
http://www.emedicinehealth.com/kidney_transplant/article_em.htm