Side effects can occur from taking generic Celexa medication. If initial symptoms of depression worsen or you start feeling any new symptoms, inform your local doctor immediately. This medicine may take four weeks or longer to show results, so this may be especially true at the beginning of your treatment. Symptoms that may develop include: mood or behavior changes or worsening depression; irritability, anxiety aggressiveness or restlessness; panic attacks; sleeping problems; or thoughts of self harm or suicide. Serious physical effects include: muscle stiffness, high fever, tremors, or heart fluctuations; headaches, problems with concentration, balance, coordination or memory, weakness, seizures; as well as others. If any of these arise after you buy Celexa, inform your local doctor immediately. Less-serious side effects may include: cold symptoms, sexual problems; insomnia; upset stomach, gas or nausea; or others. If you develop an allergic reaction to the generic Celexa medication, including hives, trouble breathing or facial, mouth or throat swelling, seek immediate medical attention.