You are unable to donate blood for 12 months after you have a tattoo and in some cases any kind of body piercing.
Does it hurt?
Pain is really relative. Everyone has a different tolerance to pain. I'm not going to kid you, though - it does hurt. Just not that much. Some have compared it to a "hot scratching feeling". But, people would not be returning again and again for tattoo after tattoo if it hurt that bad! Most of us are not in to pain, but the beauty of the tattoo and the pride associated with wearing it far outweighs a little pin-stick here and there.
Are tattoos safe?
Yes, as long as you go to a reputable artist that is following all recommended safety precautions. Find out what these recommendations are by going through the Safety Checklist.