If you had your piercing done without anaesthetic:

There will be a slight stinging sensation on the underside of your tongue that will start about one minute after the piercing has been done. This will ease gradually over about 10 minutes until your tongue returns to normal. If your tongue swells before you go to bed, the swelling usually lasts for just 24 hours. If it swells whilst you are asleep the swelling may last for up to 3 days. If it isn't swollen before you go to bed, and isn't swollen when you wake in the morning, then it isn't going to swell at all. The swelling is usually between 6 and 12 millimetres. You won't have a sore tongue but you might feel like you have swollen glands in your throat. This is actually the root of the tongue that is swollen.

This can be eased by the use of anti-inflammatory drugs such as IBUPROFEN, but remember to follow the directions on the packet and don't take more than you should. Do not take Aspirin, as this thins the blood. Cooling the tongue with ice helps to ease discomfort by reducing the swelling. It is better to eat the food that you usually eat whilst the piercing is healing.