Nig 25mg Injection is used to treat and prevent heart-related chest pain (angina). Angina occurs when the heart muscle is not getting enough blood. This medicine works by relaxing and widening blood vessels so blood can flow more easily to the heart. It has a very short-lived effect. Nig 25mg Injection is given as an injection under the supervision of a doctor with careful blood pressure monitoring. This is given as a continuous infusion into a vein and should not be stopped abruptly. It should not be mixed with any other medication of any kind. The most common side effect of Nig 25mg Injection is a headache which may be severe. This can sometimes be helped by drinking plenty of fluids and avoiding alcohol. You may also experience lightheadedness, which could increase your risk of having a fall. There are other, rarer side effects, some of them serious. Ask your doctor and read the leaflet which comes with the medicine to make sure you are keeping safe.