Vascepa is a prescription medication used to treat high levels of triglycerides in the blood. While it is generally considered safe and well-tolerated, it can cause allergic reactions in some individuals.

According to the sources provided, the onset of an allergic reaction to Vascepa can vary from person to person. Some people may experience an immediate reaction, while others may not experience symptoms until several days or weeks after starting the medication.

The most common symptoms of an allergic reaction to Vascepa include hives, itching, swelling of the face, lips, tongue, or throat, difficulty breathing, and chest tightness. In severe cases, an allergic reaction can cause anaphylaxis, a life-threatening condition that requires immediate medical attention.

It is important to note that allergic reactions to Vascepa are rare, and most people can take the medication without any problems. However, if you experience any symptoms of an allergic reaction while taking Vascepa, you should stop taking the medication and seek medical attention right away.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/VASCEPA
[2] https://www.singlecare.com/blog/vascepa-side-effects/
[3] https://www.healthline.com/health/drugs/vascepa-side-effects