What's in a pre-workout and is it safe

A pre-workout usually contains caffeine (energy, focus), beta-alanine (endurance), citrulline (pump), sometimes creatine, tyrosine, taurine.

• Skin tingling/itching comes from beta-alanine (paresthesia) — harmless, gone in 30–60 minutes.
• Flushing comes from niacin (B3) — harmless.
• Start with half a scoop; check the caffeine on the label (no more than 400 mg a day in total, counting coffee and energy drinks).
• 20–30 minutes before training, not after about 4 pm — it hurts sleep.

Not for heart or blood-pressure problems, pregnancy or under 18. Stimulant-free versions exist.