Fenspar 12.5mg Patch is a pain relieving medicine. It effectively alleviates moderate to severe chronic ongoing pain. It should not be used in mild pain. It is prescribed only in cases where other alternative pain medications are inadequate. Fenspar 12.5mg Patch is for external use only. You should use it in the dose and duration as advised by your doctor. The affected area should be clean and dry before application of the ointment. You must wash your hands thoroughly before and after applying this medicine. Vomiting, dizziness, nausea, headache and constipation are some of the common side effects that might be observed on taking this medicine. Use caution while driving or using any machinery as it might cause drowsiness or visual disturbances. Inform your doctor if you have any history of kidney or liver related problems.