The drugs you mentioned are opiates. There is no research yet that I can find on whether opiates effect on protein synthesis (muscle growth). The only thing I know is that one type of opiate (as mentioned in the previous comment) has a positive impact on cortisol levels. While newcomers to weightlifting dread the pain associated with DOMS, it's actually part of the muscle-growth process. When you challenge yourself to failure or near-failure on multiple sets for a specific muscle group, you'll likely experience DOMS after your workout. Do pain killers affect muscle growth? Over-the-counter pain killers are a popular way to ease the pain and soreness that manifests itself 24-48 hours after a tough workout. Over-the-counter pain killers are a popular way to ease the pain and soreness that manifests itself 24-48 hours after a tough workout. No effect on growth, but definite other health effects if you take too many NSAIDs. Use in moderation, just like anything. Use in moderation, just like anything. Source: friend is a pharmaceutical docotor at a hospital. Overall Study Design. This study was a randomized, placebo-controlled, double-blind, 12-wk investigation. During the 12 wk, subjects completed a progressive resistance training program of the lower extremities three times per week and consumed a placebo, acetaminophen, or ibuprofen. How Do Pain Meds Affect Muscle Growth? - Men's Fitness the placebo group experienced a 7 percent growth in muscle mass those taking either acetaminophen or ibuprofen experienced a 40 percent to 60 percent larger increase than the placebo group Specifically, muscle volume increased 11 percent in the ibuprofen group and 13 percent in the acetaminophen group, compared with 9 percent in the placebo group. A number of studies have examined the effects of Tylenol and other NSAIDS on muscle growth. The studies indicate that taking NSAIDS to relieve pain during or after your workout is counterproductive, because they inhibit protein synthesis, which in turn inhibits the growth of muscles. None of these studies found a negative effect on muscle hypertrophy (8, 14, 20). In fact, one of them showed that NSAIDs actually increased muscle hypertrophy by approximately 50% (20). You heard right, the group popping painkillers doubled their muscular gains! How to use Tylenol. Take this product by mouth as directed. Follow all directions on the product package. If you are uncertain about any of the information, consult your doctor or pharmacist.