Drug Interaction Report

Propafenone may significantly increase the blood levels of relugolix. This may increase the risk and/or severity of side effects such as hot flushes; weight gain; decreased sex drive; erectile function difficulties; muscle and joint pain; constipation; diarrhea; increases in glucose, triglyceride (fat), and liver enzyme levels; and decreased hemoglobin levels. Combining these medications may also increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. 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. If you do have to take both medications, you should take relugolix first, then take propafenone after at least 6 hours to minimize the effects of the interaction. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications, whether together or alone. 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.

Consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit should be avoided during treatment with propafenone as they may increase the blood levels of propafenone in some patients. This can cause serious side effects such as new or worsening irregular heart rhythm or heart failure; chest pain; difficulty breathing; fluid retention and swelling; and slow heart rate and pulse. Talk to your doctor if you have any questions or concerns. 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.