Currently, there are no known side effects for most hyaluronic acid products including pills, serums, creams and liquids. However, there are some side effects associated with knee and facial injections.

Some of the less common side effects for knee injections of hyaluronic acid include: blue color or flushing or redness of skin, cough, difficulty in swallowing, dizziness or feeling faint, fever, redness or pain at place of injection, skin rash, hives, and/or itching, stuffy nose, swelling of eyelids, face, or lips, as well as tightness in chest, troubled breathing, and/or wheezing.

Some of the more common side effects for knee injections of hyaluronic acid include: diarrhea, headache, itching of the skin, large blue or purplish patches in the skin, loss of appetite; nausea and/or vomiting, stomach pain and swelling of the knee.

Facial injections of hyaluronic acid gel to combat aging do not pose an allergy risk for patients. However, hyaluronic acid gel does not contain lidocaine, an anesthetic, so injections can be painful. In addition, there is usually temporary inflammation that produces swelling and redness following injection with hyaluronic acid gel especially in the lip area.