After the war, US intelligence officers discovered that Morell was pumping Hitler with 28 different drugs, including eye-drops that contained 10 percent cocaine (up to 10 treatments a day), a concoction made from human placenta and "potency pills" made from ground bull's testicles. But despite the barrage of medicines, Morell's diaries (which were recovered from Germany and are kept in the National Archives in Washington, DC) make clear that the bouts of "agonizing flatulence" remained a regular occurrence.

If he had not been so cravenly devoted to Hitler, a hero-worship he expressed over and again to US interrogators, one might have thought Morell a spy. It was a suspicion that had occurred to other Nazis, especially during the 1944 jaundice attack. Heinrich Himmler interrogated Morell's assistant Richard Weber in Berlin's Gestapo Headquarters about whether the doctor was deliberately poisoning the Führer with his treatments. "Out of the question," Weber replied. "Morell's too big a coward for that."

He was also a valerian addict.