Nausea, vomiting, constipation, or diarrhea may commonly occur during treatment with daclizumab. However, these side effects are probably caused by other drugs you are taking at the same time (e.g., cyclosporine, corticosteroids). If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: redness/pain/swelling at the injection site. This medication can lower your body's ability to fight an infection. Use of drugs that weaken the immune system may also infrequently increase your risk of developing certain types of cancer (e.g., lymphoma) years after treatment. Your doctor should monitor you closely for signs of these problems. Tell your doctor immediately if you develop any of the following signs: signs of infection (e.g., fever, persistent sore throat, cough, painful urination), poor wound healing, unusual growths/lumps, swollen glands (e.g., on the neck, in the armpits), unexplained weight loss, night sweats, easy bruising/bleeding, abdominal pain/swelling, unusual tiredness. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing, chest pain, slow/fast/irregular heartbeat, increased sweating. In a heart transplant study, use of daclizumab in combination with cyclosporine, mycophenolate mofetil, and corticosteroids may have infrequently caused an increased risk of serious (sometimes fatal) reactions. Consult your doctor or pharmacist for more details. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.