Hello, Yes it may be the side effect of taking Forecox with the following explanation. Forecox is a combination of four different drugs used in the treatment of tuberculosis. The four drugs are Isoniazid, Rifampicin, Ethambutol, and Pyrazinamide. While Forecox is generally safe and effective, it can have side effects, including weakness and drowsiness. Drowsiness and weakness are relatively common side effects of Forecox, but they are not typically severe. However, it s important to note that these symptoms can be more pronounced in elderly individuals or those with underlying health conditions. It s also possible that your relative is experiencing side effects from one of the individual drugs in the combination. For example, Isoniazid can cause drowsiness and weakness as well. If your relative s symptoms are severe or persistent, it s important to consult his doctor. They may want to adjust the dosage or switch to a different medication to manage the side effects. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Shah Hussain, General & Family Physician