Mine did all the time when I started flossing. It worried me and I temporarily stopped because of it. But my dentist promised me that the bleeding would go away if I kept up the flossing. And he was right! Now I floss or use an inter-dental brush every day, and I only bleed very rarely.
They normally bleed when you first start flossing if you haven't done it for a while, but the more regularly you floss, the less they should bleed
Mine used to, power thru it for a week or two but if it doesnt get any better see a professional, but it should get better quickly if you floss every day
Bleeding is very normal at first. If this persists longer than a few weeks perhaps consider revising your flossing technique. Forcing floss too high into your gum may not be good. The objective is to clear plaque between your teeth and where your tooth meets your gums.
People who do not floss enough to build up strength. People with gum disease and gingivitus, unhealthy oral practicioners
If you floss regularly, your gums should not bleed. If they still bleed, look up good flossing techniques. If they continue to bleed, go to your dentist as you may have an infection.
Sometimes mine do because I haven’t been consistent with flossing! I find using mouthwash gets rid of the bleeding pretty quickly