While gearing up for surgery, your surgeon will probably give you a list of medications -- both prescription and over-the-counter -- that you'll need to stop beforehand. Some medications you can skip just a day ahead of time, but others, like fish oil, you usually need to avoid long before you go under the knife.
When to Stop
One week -- seven full days -- prior to surgery, you'll probably have to completely stop taking your fish oil supplements, suggests the University of Michigan Health System. In some cases, depending on your health and the type of surgery, your surgeon may allow you to take them up to four days before your procedure. He might even tell you that you don't have to stop taking fish oil at all. Follow your surgeon's advice carefully and ask him specifically about each medication you take. Taking fish oil and certain other drugs too close to your surgery can thin your blood, causing excessive bleeding and possible problems with clotting.