Hi Kym, Thank you for your question. The recommended dose of Benadryl for the treatment of severe itching is 25-50 mg every 6-8 hours. Even when he was in the hospital, the nurses should have been giving him no more than 50 mg per injection. If he is not getting relief from the Benadryl, he could talk to his doctor about getting something else to help relieve the itching. A medication known as hydroxyzine is commonly used to treat  severe itching, and may be beneficial to your father. However, it is important to consult with his doctor before changing his medication regimen. Best of luck, Casey