It is very important that your doctor check the progress of you or your child at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.
If your or your child's symptoms do not improve, or if they become worse, check with your doctor. Continue to take this medicine as directed.
You or your child should not use astemizole (Hismanal®), cisapride (Propulsid®), pimozide (Orap®), quinidine (Cardioquin®), or terfenadine (Seldane®) while receiving this medicine because of the risk of unwanted side effects.
Using this medicine for a long time or using it too much while you are pregnant (especially during the first trimester) can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.
This medicine may rarely cause serious liver problems. Stop using this medicine and check with your doctor right away if you or your child are having more than one of these symptoms: abdominal or stomach pain or tenderness; clay-colored stools; dark urine; decreased appetite; fever; headache; itching; loss of appetite; nausea and vomiting; skin rash; swelling of the feet or lower legs; unusual tiredness or weakness; or yellow eyes or skin.
This medicine may rarely cause a serious type of allergic reaction called anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Stop taking this medicine and call your doctor right away if you or your child have a rash, itching, hives, hoarseness, trouble with breathing, trouble with swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.
Serious skin reactions can occur in certain people during treatment with this medicine. Check with your doctor right away if you or your child start having a skin rash, itching, or any other skin changes while you are using this medicine.
This medicine may rarely cause a heart rhythm problem called QT prolongation. It may change the way your heart beats and cause fainting or serious side effects in some patients. Check with your doctor right away if you or your child have any symptoms of heart rhythm problems, such as fast, pounding, or irregular heartbeats.
This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.