Medication interaction with grapefruit?

You may want to limit your consumption of grapefruit or grapefruit juice during treatment with hydroxychloroquine. Grapefruit juice can significantly increase the blood levels and effects of hydroxychloroquine, which may result in an irregular heart rate or other conduction disturbances. Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with hydroxychloroquine. 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.

https://www.drugs.com/food-interactions/hydroxychloroquine.html