how long??

For a person who has been taking Lisinopril for 2 years, how long does it take to get out of your system after you stop taking it? A co-worker was taken to the hospital last week with facial swelling, a burning sensation in her arms and a rash that looked like severe sunburn. The ER told her she was having a severe allergic reaction to Lisinopril. Now wondering how long it will take for it to get completely out of her system, as her symptoms have improved slightly, but not completely, so she thinks she was misdiagnosed. I think it's not completely out of her system yet. Any thoughts??