Detox and Withdrawal Duration. Withdrawal is the collection of side effects that occur when a drug is removed from the brain and body of someone who is dependent on it, while detox is the actual removal of the drug itself. Withdrawal from oxycodone usually starts within 8-12 hours of taking the drug, and it peaks in the first 72 hours. Symptoms generally subside in about a week, although some of the psychological effects and drug cravings may persist for longer.