This is the reason why you may want to avoid it. What happens is that grapefruit blocks a particular enzyme in the liver, preventing the liver from breaking down the med and they build up for a while in the blood stream until the liver can clear things out.
Methimazole also counteracts in the liver and it is required while on the med to have liver labs done checking that.
Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.
Do not receive a "live" vaccine while using methimazole, and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you. Live vaccines include measles, mumps, rubella (MMR), oral polio, chickenpox (varicella), BCG (Bacillus Calmette and Guérin), and nasal flu vaccine.
Grapefruit is considered a goitrogen, but I'm not sure I'd avoid it completely; I don't.
Grapefruit doesn't have to be a breakfast treat; it can be a lunch, snack or dinner treat......In fact, this evening I drank the juice of several grapefruit off the tree in my back yard......
All things in moderation so I certainly wouldn't let those "golden globes" go to waste......you might try separating them from medication by a couple hours, etc.........
Actually from what I've read grapefruit is worse for hypothyroidism than hyperthyroidism, which I assume you have since you are on methimazole.
Talk to your doctor when you can, but don't give up all the good stuff in life, unless it adversely affects you.......
I just checked Interactions for these two on Drugs.com, They stated no study has been done based on Grapefruit and Methimazole. They just advised checking with your MD, Sorry That Breakfast treat will have to wait.
I know they say not to eat or drink juice from Grapefruit when takings Statin Drugs. FTB4