Myth: People who have a tattoo cannot donate blood.
The justification behind this myth is that the blood gets contaminated once a person gets a tattoo. This is not entirely true. It is just safe not to donate blood immediately.
TRUTH: Getting a tattoo is very much similar to getting an injection. Both involve a needle which comes in contact with your blood. It’s a fact that the same needle is going to be reused on another person at a tattoo shop. The same risk of reusing a needle that has been in contact with someone else’s blood lies here in case of tattooing. While most of the good shops will be taking precautions like replacing the needle or sterilizing the needle before reuse, we cannot omit the chance of infection. It is always safe to give a 6 months gap between getting a tattoo and donating blood. Any kind of infection would have enough time to surface in that time.
So, it’s safe to donate blood after a 6 months interval. And it’s perfectly fine to receive blood from a person with a tattoo provided he got the tattoo before 6 months or more.
Some sources: Link