For the Consumer. Applies to naproxen: oral capsule liquid filled, oral suspension, oral tablet, oral tablet enteric coated, oral tablet extended release. As well as its needed effects, naproxen may cause unwanted side effects that require medical attention. Major Side Effects.
Most likely your testicle shrinkage and low sperm count were caused by inactive sexual activity for a while, sexual exhaustion due to over masturbation, and low testosterone level. Try Testicular Massage to stimulate your testicles for more blood flow.
As far as the effects of this lowered test production, at 40mg a day, I would say that it's pretty much split evenly. Half of people will attest to loss of sex drive and testicular shrinkage late cycle, while about half attest that they retained sexual drive without any shrinkage.