Revlimid does not usually cause weight gain, in fact, 7% to 20% of people in clinical trials report losing weight while taking Revlimid, but RAPID weight gain may be a sign of a serious side effect such as fluid retention or tumor lysis syndrome, and you should call your doctor immediately.
Symptoms of fluid retention include swelling in the feet, ankles, or face and rapid weight gain. Some people may also feel short of breath if fluid has built up in their lungs. Notify your healthcare team if you have any swelling, unexpected weight gain, or shortness of breath.
Tumor Lysis Syndrome (TLS) is a life-threatening condition that occurs when a large number of cancer cells die within a short period, releasing their contents into the blood. Symptoms of TLS include pain in the joints, back, side, or stomach; swelling of the feet or lower legs; a decrease in the amount of urine; a rapid weight gain, or unusual tiredness or weakness. Call your doctor right away if you have any of these symptoms.