Hydromorphone and oxymorphone are full agonist opioids and with potencies 5-10 fold greater than morphine. Their duration of action is similar to morphine. Unlike morphine, these two do not produce histamine release and are considered safer for intravenous bolus administration. Upon intramuscular injection, though, some patients will vomit. Both of these drugs are routinely used to manage acute pain and in the peri-anesthetic period in veterinary patients.