Antibiotics - performance nocebo?

Medical Q&A [Moderated]
1

Hi docs,

Thanks for all the help you give.

I am on Flucloxacillin for impetigo infection, I’ve had to take it for 7 days. I am almost done with it and infection seems to have gone.
Just want to ask: does taking antibiotics have any acute or long term affect on athletic performance, particularly endurance performance? This might be dumb but I’ve skipped my conditioning workouts and been focusing on lifting, as I’ve read/heard that antibiotics really ‘drains’ you and runners have complained about it making them slow. Is there any evidence or hypothetical reasons to explain this? All I saw was some research on how VO2max was the same after 3 days on antibiotics.
Do you think I should do my conditioning workouts as normal? I want to improve on my conditioning for my sport, hence why I’ve been skipping in case my performance were to be attenuated by antibiotics and then the workout would be unproductive.

Personally, my energy has felt perfectly fine. Strength has been the same in the gym. So I’m just more so asking in relation to endurance performance. I might be overthinking it, but I’m interested to hear an informed Dr’s opinion and how others have felt too.

Many thanks

2

I wouldn’t have any concerns about your performance after taking this antibiotic, and would program them as normal, autoregulating intensity as needed (e.g., using RPE).

Skipping workouts is more unproductive than doing workouts, even if your performance were reduced (… which is not the case from an antibiotic, whereas performance is more likely to be reduced from an uncontrolled/untreated infection).

3

My personal anecdotal evidence, maybe or even probably a placebo, but I was on Penicillin twice and on Amoxicillin twice, and during all 4 times my endurance (swimming in my case) was better than before taking the antibiotics. After the first time, I have also tested some drills in the last 3 times and scores were way better than expected / than was done, say, 2 weeks earlier.
Very well may be a placebo though.