I was given Colofac (Mebeverine) by my doctor for flatulence and gas - won't this medicine cause side effects if I take Omeprazole and Mirtazapine in addition?

Like any drug, a product containing mebeverine can cause side effects (although, of course, not in every patient). In people sensitive to the active ingredient of the drug, local skin irritation may occur, e.g. rash and red spots. If you experience serious side effects resulting from a severe allergic reaction (e.g. shortness of breath, swelling in the face and neck), you should see a doctor immediately. There was no evidence of an interaction between the mebeverine-containing medicine and the other medicines you were taking. If you take several preparations during the day, it is worth keeping the interval between tablets - then the risk of disturbing the mechanism of action of active substances is reduced. I encourage you to read the article: https://www.gdziepolek.pl/artykuly/czy-bac-sie-dzialan-niepozadanych-lekow https://www.gdziepolek.pl/artykuly/czy-przyjmowanie-kilku-lekow-jednoczesnie-jest-bezpieczne