A jammed thumb is typically a sprain to the joint or knuckle of the thumb, which can be extremely painful and cause swelling. Here are some steps you can take to treat a jammed thumb:

• Rest: Try not to use your hand for at least 48 hours after the injury.
• Ice: Apply ice to the affected area immediately after the injury to reduce swelling. Use cold packs for 20 minutes at a time, several times a day. Do not apply ice directly on the skin.
• Compression: Wear an elastic compression bandage to reduce swelling. Do not make the bandage too tight, as this could cut off blood flow to the thumb.
• Elevation: As often as possible, rest with your hand raised up higher than your heart to reduce swelling.

If the pain and swelling persist or become worse, or if you cannot move your thumb, it is important to seek medical attention. A healthcare provider can evaluate the injury and determine if there is a fracture or dislocation of the joint, and recommend appropriate treatment such as a splint or physical therapy.