A medusa piercing is quite similar to the labret and can be found below the nose on the top lip. It is done in the philtrum, which is the small indent just below your nose. Normally a labret is used as jewelry in such piercings.
Since the piercing involves the top portion above the lip and the one end is within the mouth, you need to take care of the piercing on both ends. Once the piercing is completed, you have to follow the instructions in a different manner for each end of the piercing. You will find that in the first week following the piercing, you will find that eating and drinking will also be difficult. You need to avoid smoking totally. The consumption of alcohol should be limited to clear drinks and the consumption of beer should be avoided as the yeast could cause problems.
As for the jewelry that you can start with, you can use a 14 or 16 gauge labret stud. Normally the piercing is done with an extra long stud so that any swelling can be accommodated. You will find that the swelling comes down as the healing process takes place. The complete healing process will take about 6 months but you will start feeling relatively comfortable after anywhere between 6-8 weeks. If you find that you still have problems after this then you should visit the doctor.
When you find that things are comfortable after the 1-1.5 months time period has elapsed, you may go to the piercer to get a stud with a shorter bar.
As with any piercing do make sure that this is what you want, do the research on the piercer, be sure that you can deal with the pain and the after care required before you proceed with the piercing. This may help you in Medusa Piercing: