For the treatment of tenosynovitis in the thumb, several approaches can be considered. Rest is crucial. Try to avoid overusing the thumb and give it sufficient time to recover. Applying ice to the affected area can help reduce inflammation and relieve pain. You can also use a thumb splint to immobilize the joint and provide support. Over-the-counter anti-inflammatory medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), may be taken to ease the swelling and pain. In some cases, physical therapy may be recommended, including exercises to improve range of motion and strengthen the surrounding muscles. If the condition is severe or does not improve with conservative treatment, a doctor may consider injecting corticosteroids or, in rare cases, surgical intervention. It's important to follow the doctor's advice and take proper care to promote healing and prevent recurrence.