Yes, Benlysta can cause an allergic reaction, but serious and life-threatening allergic reactions are uncommon. Approximately 13% of people will experience a mild to moderate hypersensitivity (allergic) reaction on the day they get their Benlysta infusion. This is an exaggerated or inappropriate response by our immune system to Benlysta, which can also occur with other medications. Symptoms include low blood pressure, swelling under the skin (angioedema), urticaria (hives), other rashes, itch, and shortness of breath. Anaphylaxis, a very serious, life-threatening reaction, has only been reported in 0.6% of people receiving Benlysta (9 people experienced anaphylaxis out of 1458 people who were given it).
People may also experience an infusion reaction on the day they get their Benlysta infusion, and sometimes it is difficult to tell if this is a true infusion reaction or a hypersensitivity reaction, because there is an overlap of signs and symptoms. 17% of people experienced mild to moderate infusion reactions (251 out of 1458 people receiving Benlysta) and the most common symptoms include a headache, nausea, and skin reactions. Serious infusion reactions have been reported in 0.5% of people receiving Benlysta and symptoms include a slow heartbeat, muscle aches, headache, rash, urticaria, and low blood pressure.
Hypersensitivity reactions, infusion reactions, and serious allergic reactions such as anaphylaxis can occur when Benlysta is given subcutaneously or by intravenous infusion. The risk of hypersensitivity reactions is greatest with the first two doses of Benlysta, although the risk should be considered for every administration. Reactions are more likely to occur within a few hours of administration, but delayed reactions have been reported. Allergic reactions to Benlysta are more likely to occur in those with a history of multiple drug allergies or significant hypersensitivity, but appear less common in people who have received premedication to reduce the risk of an infusion/allergic reaction.
You should seek immediate medical attention if you develop any signs or symptoms of a hypersensitivity reaction such as itchy skin, low blood pressure, muscle aches, nausea, swelling under the skin (angioedema), urticaria (hives), other rashes, or shortness of breath.