Side effects are generally very mild
In regards to any side effects present from fish oil, this greatly depends on the brand you are using, as well as your body. If you begin to experience any GERD-like symptoms, mild diarrhea or headache, you should try taking smaller doses throughout the day. Some people also report fishy-smelling breath or burps. If any of these symptoms persist or worsen, you should seek immediate medical attention. Keep your doctor updated so you can manage treatment accordingly.