Caffeine attenuates vasovagal reactions in female first-time blood donors

The experience of vasovagal reactions during blood donation (e.g., faintnes s, dizziness, Lightheadedness) can be a deterrent to repeat donation. Becau se these reactions are associated with decreases in blood pressure, caffein e was examined as a potential modulator of vasovagal reactions by virtue of its presser effects. Using a randomized, double-blind design, 62 female un dergraduate Ist-time blood donors received either 0, 125, or 250 mg of caff eine prior to blood donation. Participants who received 250 mg of caffeine had lower scores on the Blood Donation Reactions Inventory, required fewer interventions by phlebotomists for negative reactions, and reported a great er likelihood of repeat donation than participants who received placebo. Th ese findings suggest that a moderate dose of caffeine attenuates negative r eactions in novice female blood donors and may increase the likelihood of r epeat donations.