How do you recommend treating tenosynovitis?

In the Hand? This is most commonly a hand condition. If so, this is treated with nsaids like ibuprofen, a wrist brace limiting the motion of the involved tendon, ice over the tendon, reduction in usage of the involved tendon for many days and often weeks. If no improvement after several weeks and it is really bad then injections with small doses of corticosteroids is next. Surgery after months of no improveme.