My hamster has a red tip on her tail. What could it be?
Do you have maore than one? a lot of times hamsters will nibble on each other's tails when in their way or "playing" they can be territorial. Or it could have been caught in a wheel. I'd say watch it carefully for infection, and make sure you keep the cage very clean. Because of the way hamsters excrete waste their cages are full of bacteria. Ask A local pet store what they recommend. I believe there is a rodent salve that seals scrapes of that nature.
Your hamster's tail could have been scraped or banged.