HGH is relatively benign in the side effects department.
Possible side effects of HGH use include:

*nerve, muscle, or joint pain
*swelling due to fluid in the body's tissues (edema)
*carpal tunnel syndrome
*numbness and tingling of the skin
*high cholesterol levels

Possible side effects of caffiene:

*stomach pain, tenderness, bloating,
*constipation or diarrhea;
*green-colored vomit;
*blood in the stools;
*unusual weakness;
*seizure (convulsions);
*twitching or uncontrolled muscle movements; or
*fever, fast or slow heart rate.

The issue is that human beings are not meant to be this big, fast and strong while colliding with each other.

For the record, the long term effects of HGH are unknown. No one is monitoring dosage and purity.

When my physician administers a medication to me, it is started in small doses along with lab tests to monitor the effects on my body.

So, your "Bro-Science" argument is invalid.