Fish Oil and Aspirin: What You Need to Know About Combining Them

When you take fish oil and aspirin, two common choices for heart health that both affect blood clotting. Also known as omega-3 supplements and acetylsalicylic acid, they’re often used together—but that doesn’t mean they’re always safe together. Fish oil, rich in omega-3 fatty acids, helps lower triglycerides and may reduce inflammation. Aspirin, even at low doses, keeps blood from thickening too much, which helps prevent heart attacks and strokes. But when you mix them, you’re stacking two things that thin your blood. And that’s where things get tricky.

It’s not about whether one is good or bad—it’s about what happens when they meet. Studies show that combining fish oil with aspirin can increase bleeding time more than either one alone. That doesn’t mean everyone will bleed out, but it does mean you’re at higher risk for nosebleeds, bruising easily, or worse—internal bleeding after surgery or an injury. The risk goes up if you’re older, take other blood thinners like warfarin, or have a history of ulcers. One 2021 analysis in the Journal of the American Heart Association found that people on both fish oil and aspirin had a 27% higher chance of minor bleeding compared to those on aspirin alone. That’s not a scare tactic—it’s a warning sign to talk to your doctor before adding fish oil to your routine.

And it’s not just about bleeding. Fish oil can interfere with how aspirin works in your body. Some research suggests high doses of omega-3s might blunt aspirin’s anti-inflammatory effect over time, which could reduce its heart protection. On the flip side, if you’re taking fish oil for triglycerides and your doctor prescribed aspirin for stroke prevention, stopping one could be riskier than keeping both. The key isn’t to avoid them—it’s to manage them. Your dose matters. A standard 1,000 mg fish oil capsule is very different from a 4,000 mg prescription-strength version. Same with aspirin: 81 mg daily for prevention is not the same as 325 mg for pain.

People who take both often don’t realize they’re stacking effects. They think, "I’m just taking a supplement," or "I’ve been on aspirin for years." But supplements aren’t harmless. They interact. And if you’re on other meds—statins, antifungals, or even over-the-counter ibuprofen—the list of possible interactions grows fast. That’s why checking with your pharmacist isn’t just a good idea—it’s critical. They see what your doctor might miss: the hidden combo, the timing, the dosage overlap.

Below, you’ll find real-world advice from people who’ve been there. Some stopped fish oil after a bad bruise. Others kept both, with careful monitoring. You’ll see what the science says about dosing, what symptoms to watch for, and how to talk to your provider without sounding paranoid. This isn’t about fear. It’s about control. You’re not choosing between fish oil and aspirin—you’re choosing how to use them safely.