Side effects of generic Benicar medication may include signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. In rare cases, It can also cause a condition that results in the breakdown of skeletal muscle tissue, leading to kidney failure. Call your local doctor right away if you experience muscle pain, tenderness, or weakness especially if you also have fever, nausea or vomiting, and dark colored urine. Other serious side effects may be feeling like you might pass out; painful or difficult urination; urinating less than usual or not at all; chest pain, fast heart rate; swelling in your hands or feet; or slow heart rate, weak pulse, tingly feeling. Less serious side effects may include runny or stuffy nose, sore throat, cough; joint pain; back pain; stomach pain, diarrhea; headache, dizziness; mild itching or skin rash; weakness; or increased sweating.