What can cause your thumb to swell and then go black blue?

- Sprains and strains: A sprain is an injury to a ligament, while a strain is an injury to a muscle or tendon. Sprains and strains can occur when the thumb is bent or twisted in an unnatural way.

- Fractures: A fracture is a break in a bone. Fractures can occur when the thumb is subjected to a significant amount of force, such as a fall.

- Dislocations: A dislocation occurs when a bone is forced out of its normal position. Dislocations can occur when the thumb is hyperextended or bent in an unnatural way.

- Infections: Infections can cause swelling, pain, and discoloration in the thumb. Infections can be caused by bacteria, viruses, or fungi.