Each dose of trimethoprim-sulfamethoxazole should be administered with a full glass of water, and the client should maintain a high fluid intake to avoid crystalluria. The medication is more soluble in alkaline urine. The client should not be instructed to taper or discontinue the dose. Clients should be advised to use sunscreen since the skin becomes sensitive to the sun. Some forms of trimethoprim-sulfamethoxazole cause urine to turn dark brown or red. This does not indicate the need to notify the HCP.