Aspirin & other Pain Killers’ Effects on Muscle Growth

November 1st, 2007 by Paul Johnson

A few years ago, research started coming out about the effects of common OTC painkillers effects on muscle growth. If you are new to bodybuilding in recent years, you may have missed the big news when it first came out. Many bodybuilders take them to relieve DOMS (muscle soreness) from weight training or some other ailment and don't know about this side effect. This is also important to know because many fat burning supplements, such as hydroxycut hardcore, put willow bark ( natural form of aspirin ) in it. Acetaminophen ( Tylenol ) and the class of drugs called NSAIDS , which includes the OTC painkillers, ibuprofen (Advil, Motrin) and naproxen ( Alleve ), all have an effect on protein synthesis.

Studies on painkiller effects on protein synthesis:

One of the first studies to come out was published in
J Clin Endocrinol Metab. 2001 Oct;86(10):5067-70. It was done on 24 males to either receive ibuprofen, acetaminophen or a control after resistance excercise workout (10 - 14 sets). It showed that acetaminophen and ibuprofen had an impact on prostoglandins (in equal degree). Researchers concluded this impact on prostoglandins could have a big impact on muscle growth.

One year later, these same researchers published (Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E551-6.) measuring protein synthesis after resistance workout. The study was done on 24 males who either took acetaminophen, ibuprofen, or control. Results showed that the placebo group had 75% higher protein synthesis at the skeletal muscle than the ibuprofen or acetaminophen group. These painkillers didn't effect overall body breakdown, but did effect protein synthesis at the muscle.

Aspirin also has a effect on decreasing protein synthesis. (source: J Biol Chem. 2007 Apr;282(14):10164-71. Epub 2007 Feb 6.)

Most of the older studies discuss protein synthesis, but a more
recent study published in (Med Sci Sports Exerc. 2006 May;38(5):840-6.) compared overloading a rat muscle with or without ibuprofen on actual muscle growth. Results showed reduced muscle hypertrophy (muscle growth) by 50% in rats from ibuprofen with overload vs. overload only.

As you can see these were not minor changes in protein synthesis. Even occasional use will have a significant impact on muscle growth.

  1. aliquis on December 10th, 2007

    What about those gels? They will reach the blood stream somewhat but I guess their effect is more local, will they affect the whole body or only the muscles you put them on?

  2. Admin on December 10th, 2007

    Thanks for your question. I’m not sure which gel you are talking about, but the stopping of protein synthesis is only for pain killers such as tylenol and aspirin. The pain killers seem to stop the inflammatory response of prostoglandins locally, so therefore these pain reliever through a localized gel would probably only affect the muscle you apply it to. There is always going to be some systemic leakage into the bodies circulation with any kind of topical solution, but probably not a lot.

  3. tyus on March 17th, 2008

    i just started going to the gym a few days ago and have the serious joint pains. cant even raise my arms to my face let alone put food in my mouth.
    was wondering if there were any drugi can take to relief my pain..

  4. admin on March 22nd, 2008

    Tyus you probably don’t have an injury, if your new to the gym and you have a big workout you can get pretty sore and stiff. As you go to the gym regularly in the future, you won’t experience that muscle soreness and stiffness in the joints. If you want to take asprin or something else over the counter to alleviate the pain that is up to you.

  5. Ian on March 31st, 2008

    what about opiate painkillers? I am prescribed for an old injury but if they are negatively affecting my ability to build i think i’d prefer the pain.

  6. admin on April 1st, 2008

    Opiates actually might be beneficial for muscle building for other reason. I’m not advocating their use though, but here is one reason why I think that may be the case, read this:

    Imodium (loperamide) is an opiate, so thats why im referring you to reading that.

  7. John H on July 8th, 2008

    I am currently taking many painkillers for a problem with my lower back. i am able to train to a certain level, however my muscles are waisting. Is this because of my medication. dyclophenic, dihydrocodiene, amytriptaline, diazapam… I have no energy and burn out really quickly. iu have searched the web for answers but have not been able to find any answers

  8. admin on July 13th, 2008

    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. But I don’t know if opiates actually decrease protein synthesis or if any other opiates decrease cortisol levels too.

  9. Simon on July 17th, 2008

    Hi Admin,

    Only one of the medicines John mentioned are opiates (dihydrocodiene) the others are an asprin like NSAID (Diclofenac) and muscle relaxants/mood stabilisers.



  10. admin on July 19th, 2008

    You are right Simon. Thanks for the correction. I meant to say some of them are opiates.

  11. Christian on October 2nd, 2008

    Hi Admin,
    You state in your response on Dec 10th 2007 that “…the stopping of protein synthesis is only for pain killers such as tylenol and aspirin”. These are the NSAIDs that have been researched in the articles quoted but as the authors put it, the mechanisms HOW they do it is unclear. Therefore, we cant’ really say that it’s pain killers ONLY that stop the protein synthesis, we can only say that AT LEAST pain killers stop it. There can be others that stop the process aswell. I’m thinking of several natural remedies such as Rosehip (Rosa canina) that are used to treat inflammatory processes. What if it is exactly this inflammatory process that is required for protein synthesis? Isn’t it the cellular level damage on muscles caused by exercise that causes protein synthesis? Isn’t it possibly that it is an inflammatory process, on a cellular level?

    My problem is that I have rotator cuff problems which is, if I’ve understood correctly, an inflammatory process. Rather than treat it with medicines, I’ve resorted to physiotherapy only. Problem is that I don’t seem to be able to get rid of it (it has gotten better but not good) and I may have to take medicines before it turns chronic. I’ve been considering natural remedies but this issue is bothering me. Well, it’s really a no-brainer: would I rather have somewhat larger muscles with chronic rotator cuff problems or somewhat smaller muscles with healthy shoulders?

  12. admin on October 26th, 2008

    I’ve recently come across some new studies that seem to now contradict these earlier studies on pain medication and effecting protein synthesis. At this point I’m not sure which group of studies are right, so I’m holding off updating this article until more research comes out.

  13. biff on January 16th, 2009

    hi admin
    I have question about opiates is it true that they raise growth hormone but deminish testosterone levels to low for the growth hormone to com pensate for it.
    and what about diazapam and xanax that is something ive heard nothing about

  14. biff on February 10th, 2009

    i have another question ive recently been sick of a bronchial infection and have been taking tussionex pennketik syrup and i understand it has hydrocodone a very potent opiate and ever since i started weight training i do not even take asprin so i took it only once but i took an ounce but was only supposed to take a teaspoon because it felt so good and about two years ago i used to drink it instead of alcohol to feel good with marijuana but i understand that opiates bring down testosterone levels bad and when i took that ounce i slept 30 hours straight my question is how long will it take for my testosterone levels to come up becuase i feel sleepy still and what can i do to bring them up naturaly i recently started watching adult movies because some websites say that will help is that true or is the stess i get from my girlfriend for watching them raising my cortisol to high for that to help?

  15. biff on February 25th, 2009

    i am looking for a supplement called muscle builder 3 used to have a link up top do you know where it went

  16. admin on February 28th, 2009

    Biff do you have studies that show opiates lower testosterone? it seems likely but I haven’t researched on that aspect of them yet. I just know that they do lower cortisol which is beneficial to building muscle. To answer your question, no adult movies won’t raise your cortisol high. Instead they do temporarily raise testosterone according to studies, but I don’t think it would have much of an impact on muscle building since its temporary.

  17. Christian on November 22nd, 2009


    Do you have the references to the studies that contradict the earlier findings? Searched Pub-Med with ‘NSAID’ and ‘protein’, and ‘aspirin’ and ‘protein’ without luck.

  18. Matt on November 27th, 2009

    In response to Christian:

    I too injured my rotator cuff. The point of the physiotherapy is to bring down the inflamation level of the injury and allow for proper muscle response when muscle growth appears. Otherwise you may have muscles working angainst each other thus creating more pain and knots in the muscle.

    Your best bet is to bulk up. Heavy weight lifters increase muscle mass to protect joints and muscles. I’ve seen a guy bench 350lbs and he looked like he weighed 180lbs. He risks cartilage damage and bone damage due to a lack of bone density. What you decide is entirely dependent on your intentions with your body. Bulk then tone. No chemicals just natural. Resistance training will help and never isolate. Hope that helps.
    To the Admin: would A535 and Robaxacet decrease my possibilities of muscle growth? As I understand it’s not the specific chemicals that hinder growth but it’s what they are mixed with and at what level the dose. This in turn combined with the different medications and chemicals in your body define their outcome. ie. Too much iron has one outcome versus too much potassium.

    Please tell me your thoughts.

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  20. Don on September 24th, 2010

    This is an old article, but in Oct. 08 Christian posted about inflammatory problems in the shoulder. I am experiencing the same issue with my rear delt. I believe it a cause of muscle imbalance. This is the second time its acted up. The first time I went through therapy without and OTC meds. I would like to avoid the therapy for scheduling issues and I can do the excercises on my own time when I can fit it in at my gym. My question is is there something that I can use that will not effect synthesis at the muscles?

  21. Sir Osis of Liver on December 16th, 2010

    Most medicines containing Vicodin,or their generic counterparts, namely Hydrocodone, have an unhealthy dose Acetominophen as well. How and why combining two drugs that are notoriously bad for your liver is a mystery. Either way, using one of these opiates for pain relief will not avoid the purported issue of reduced protein synthesis. Connective tissue pain is going to require some medication. DOMS on the other hand is an issue that every lifter should be able to deal with. Knowing the difference is key, connective tissue pain is constant, and DOMS should only occur when the muscle is touched or used. The best results I have had in relieving DOMS has been a light workout of the same muscle groups 24 to 48 hours after the initial workout.