Fish Oil and Swelling

iFish Oil Capsules image by Isabella from

If you develop swelling anywhere in your body while taking fish oil supplements, you should discontinue using them and call your doctor. Swelling is the primarily symptom of an allergic reaction that could potentially lead to anaphylaxis. An allergic reaction is possible to fish oil pills, especially if you’ve been diagnosed with a fish allergy. Although fish oil does not contain fish proteins, fish protein by-products may trigger an allergic reaction. Your doctor will be able to provide you with a clinical diagnosis and treatment options.

Fish Oil Allergy

Taking any dietary supplement can cause an allergic reaction. Fish oil supplements may trigger an allergy if you’re allergic to fish. When you ingest the fish oil supplement, your immune system makes a mistake that triggers a chemical reaction throughout your body. The immune system accidentally identifies the fish oil supplement as a threat to the body and produces immunoglobulin E antibodies to fight against the supplement. Immunoglobulin E antibodies cause histamine production in soft tissue throughout the body, which leads to swelling and irritation.

Respiratory Swelling

The respiratory system is one of the common places that soft tissue becomes inflamed. If swelling develops in your respiratory system you may develop sinus congestion, sinus headaches, pressure in your head, wheezing, coughing, trouble breathing, shortness of breath and chest tightness. Most respiratory swelling will not lead to further complications, but if you become lightheaded, dizzy and are unable to breathe, call 911 immediately.

Concerning Swelling and Symptoms

Swelling that occurs in your face, lips, tongue or throat are concerning symptoms. These symptoms are related to a life-threatening condition called anaphylaxis, commonly related to a fish allergy. The sensation of a lump in your throat may be a sign that your throat is swelling. Your skin may also swell, causing the formation of hives or an itchy rash. Hives are a skin rash that develops welts on your body that are red and itchy. Hives do not pose a threat unless they develop in your throat or airways.


If the swelling is a result of an allergic reaction to fish, your doctor will recommend you avoid taking fish oil supplements. You can take alternative supplements that do not contain any fish to acquire omega-3s, such as flax oil supplements. In order to properly treat your condition, your doctor may recommend that you see an allergist for a clinical diagnosis using the RAST skin test. A RAST skin test uses a small amount of fish proteins that are injected under your skin to determine if your skin reacts to the suspected allergen.