Fastel 120 belongs to a group of medicines called antihistamines. It is used to treat various allergic conditions such as hay fever, conjunctivitis and some skin reactions such as eczema, hives and reactions to bites and stings. It also relieves watery eyes, runny nose, sneezing, and itching. Fastel 120 should be taken on an empty stomach. The dose may vary depending on what you are taking it for. Take it as prescribed by your doctor. You may need this medicine only on days you have the symptoms, or you may need to take it every day to prevent the symptoms from happening. If you stop taking it earlier than advised, your symptoms may come back. This medicine is generally very safe. The most common side effects include headache, drowsiness, dizziness, and nausea. These are usually mild and go away after a couple of days as your body adjusts. Consult your doctor if any of the side effects persist or worry you. Before taking it, tell your doctor if you have any problems with your liver or kidneys or with your heart as antihistamines can cause your heart to beat faster. Pregnant or breastfeeding women should also consult with their doctor before taking it. Avoid drinking alcohol as it can cause excessive drowsiness with this medicine. It usually does not impair your ability to drive, but you should not drive if it makes you feel sleepy or dizzy.