In rats and mice, phenoxybenzamine has been found to increase the risk of development of malignant tumors. It is not known if phenoxybenzamine increases the risk of tumors.
Along with its needing effects, a drug may cause some unwanted effects. The following side effects may go away as your body adjusts to the drug. However, check with your family doctor if any of these effects continue or are bothersome:
More common
Dizziness or lightheadedness, especially when getting up from a lying or sitting position; fast heartbeat; pinpoint pupils; stuffy nose
Less common
Confusion; drowsiness; dryness of mouth; headache; lack of energy; sexual problems in males; unusual tiredness or weakness
More common side effects not listed above may also occur in some diseaseds. If you notice any other problems, check with your family doctor.