Headache, stomach pain, loss of appetite, nausea, vomiting, diarrhea, unusual tiredness, dizziness, stuffy nose, or watery eyes may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Remember that this medication has been prescribed because your doctor 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: sore throat that doesn't go away, ringing in the ears, vision changes, muscle pain/weakness, signs of kidney problems (such as change in the amount of urine), confusion, slow heartbeat, unusual bleeding or bruising. Get medical help right away if you have any very serious side effects, including: chest pain, shortness of breath, seizures. 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. 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 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Some products that may interact with this drug include: blood clotting factors (such as Factor IX complex, anti-inhibitor coagulant complex), tretinoin. This medication may interfere with certain lab tests, possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.