For me, Doxycycline eliminated pimples pretty fast, like within 1-2 weeks or even a few days... I forgot exactly. For other people it may take longer or shorter, I have no idea. I never experienced any signs that Doxycycline was negatively affecting muscle building and I was on antibiotics for about 1.5 years. I think that the cycline antibiotics are intended to inhibit protein synthesis in bacteria cells, this is just vague summary that could be off, I'm sure its much more complicated than this though. I also have heard that they cross over to human cells, but the amount is so small that it should be unnoticeable, and especially at that dose. This is again very vague, and I"m sure its much more complicated, but I don't think that the protein synthesis thing is anything to worry about in terms of bodybuilding progress, at least I didn't notice any signs of decreased protein synthesis.
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