Drug Interactions between dapsone and trimethoprim

Using dapsone together with trimethoprim may increase the risk and/or severity of side effects such as nausea, vomiting, abdominal pain, liver problems, and impaired bone marrow function resulting in low numbers of different types of blood cells. You may be more likely to develop anemia, bleeding problems, and infections because of low blood cell counts. Of particular concern is the potential development of hemolysis, which is the premature destruction of red blood cells, and methemoglobinemia, a blood disorder that leads to impaired ability of red blood cells to distribute oxygen to tissues. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. You should seek medical attention if you develop headache, fatigue, dizziness, lightheadedness, fainting, shortness of breath, exercise intolerance, sore throat, fever, unusual bleeding or bruising, and paleness or a bluish discoloration of the skin. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.