A hidden poison many of us use without realizing it.

Aspirin — acetylsalicylic acid — is a painkiller and blood thinner that needs no introduction. In the bodybuilding scene it gets taken on steroid cycles with the intention of "preventing clots and protecting the heart," and it also features in old, famous gym cutting stacks. This article is not about its medical use under prescription — that is a doctor's territory and not our subject. This is about taking it on your own, for the cycle.

Aspirin works by blocking the cyclooxygenase enzyme (COX), the enzyme responsible for synthesizing prostaglandins — which is why it has an anti-inflammatory effect.

***Source 1

And here is the first problem: prostaglandins — and inflammation signalling in general — are essential to the muscle-building process. Which means aspirin acts directly against muscle growth, suppressing it by opposing prostaglandins. The effect shows up hardest with continuous use over long periods.

***Source 2

It does not stop there.

Aspirin also inhibits the mitochondria in your cells — the part responsible for burning calories and producing energy — and through this pathway it drives slow, programmed cell death.

***Source 3

And one more.

Aspirin suppresses platelet function (that is where the blood-thinning comes from), and through that same mechanism it also increases the rate of fat accumulation — even with light use, as long as it is daily and continuous.

***Source 4

"But people take it for the heart?"

This is exactly the line between a medical decision and a gym decision. Some people genuinely need aspirin for their heart — prescribed, diagnosed, monitored. That is a legitimate medical case. Taking it on your own as a "precaution" while on cycle means paying with your muscle and your cells for something you may not need at all — or for which a doctor would have chosen something entirely different.

And protecting the heart on cycle is a much bigger subject than a blood-thinning pill. That is the next article in this series, and we will open it from the roots: why steroids shorten the heart's lifespan in the first place, and what actually protects it.

The sources are listed for anyone who wants the full detail on aspirin's mechanism and its effect on us.