Is the medicine used in clinical trial actually meant to help participants?

Depends on trial: Some clinical trials pit one drug against another to compare their efficacy for certain conditions. Others pit a drug against a placebo to learn how well the drug works; then those who received placebo get drug & others get placebo to see if results are consistent. It would be unethical to give drugs that might intentionally harm patients; that's why some studies stop early due to dangerous effect.