Thumb tendonitis symptoms are mainly pain at the thumb side of the wrists, between your hand and your arm. Other notable symptoms for tendonitis of the thumbs could be tenderness and spasms around the wrist area, near the large pointy bone (scaphoid bone). Sometimes the tendonitis can cause swelling over and around the thumb side of the wrist, or cause a mild burning sensation. These manifestations can and will cause difficulty gripping and overall lack of hand motor skills. Usually these symptoms grow over time and can become unbearable. Even though we are talking about tendonitis of the thumb, the pain can often travel up into the forearm and elbow, and all the way to the pinkie side of the hand.