M-Fost 500mg Injection is used to prevent dryness in the mouth after radiotherapy of head and neck cancer. It reduces the harmful effect of chemotherapy on the kidneys during treatment with cisplatin (medicines used to treat cancer). M-Fost 500mg Injection is given as an injection into vein (IV infusion) under the supervision of doctor. Your doctor will decide what dose is necessary and how often you need to take it. This will depend on what you are being treated for and may change from time to time. You should take it exactly as your doctor has advised. Taking it in the wrong way or taking too much can cause very serious side effects. It may take several weeks or months for you to see or feel the benefits but do not stop taking it unless your doctor tells you to. Nausea, vomiting, decreased blood pressure, sleepiness, dizziness, and flushing are some common side effects of this medicine. Consult with your doctor if it does not go away or bothers you. It is advised to stay hydrated before taking this medicine. You will be check for blood pressure before infusion and every 5 minutes during infusion. Before taking it, tell your doctor if you have heart diseases such as irregular heartbeat and heart failure, or are taking any medicines to treat infections. Many other medicines can affect, or be affected by, this medicine so let your healthcare team know all medications you are using.