OK–so this is something I have wondered for a while. Do NSAIDs like ibuprofen block muscle growth after a workout? These drugs dampen down pain by blocking the COX pathway, but that pathway is also part of the signal that produces muscles growth. In short, the inflammatory process that produces sore muscles after a workout is what tells the muscles they have to grow more. So if you take ibuprofen to ease the soreness, will that also inhibit muscle growth. Various articles I have read do not give a definitive answer.
This study from 2008 does, and it is kind of an ironic result. Through a double-blind, placebo control trial they determined that moderate doses of ibuprofen (400mg a day) does not inhibit muscle growth after workout. But here is the kicker: the same trial showed that this dosage also didn’t diminish muscle soreness. So you can take it with no detrimental effects on muscle growth. But it’s not going to make you feel any better.
The effects of ibuprofen on muscle hypertrophy, strength, and soreness during resistance training. – PubMed – NCBI.