How long does it take for low dose naltrexone (ldn) to get completely out of your system?

Days: Naltrexone creates and active metabolite. It may be 6 to 7 days untill both are completely out of your system.

Several days: Naltrexone is a short half-life drug, but has a longer half-life metabolite, with a half-life of about 14 hours. This means after one day only 1/4 of the original drug is left, and after 2 days about 1/32 of the drug. It somewhat depends, if urine drug testing is being done, on how sensitive the test being used is, and what their cut-off is (usually 50 ng/ml). Again, after 72 hours, prob neg.