Drug Interactions between promazine and siponimod

Before starting siponimod, let your doctor know if you are currently receiving treatment with promazine. Using siponimod in this situation can increase the risk of an irregular heart rhythm that may be serious or life-threatening. This is most likely to occur within 5 to 6 days after starting treatment with siponimod. Talk to your doctor if you are uncertain whether you should be treated with these medications at the same time. Contact your doctor if you develop dizziness, lightheadedness, fainting, shortness of breath, chest pain, or heart palpitations during treatment.

Combining these medications can also increase the risk of serious infections. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Because siponimod can remain in your blood after the last dose, interactions with other drugs may occur for some time even after you have stopped taking it. Contact your doctor immediately if you develop signs and symptoms of infection such as fever, chills, diarrhea, sore throat, muscle aches, shortness of breath, blood in phlegm, weight loss, red or inflamed skin, body sores, and pain or burning during urination. 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.