Barely visible needles, or “microneedles,” are poised to usher in an era of pain-free injections and blood testing. Whether attached to a syringe or a patch, microneedles prevent pain by avoiding contact with nerve endings. Many microneedle products are moving toward commercialization for rapid, painless draws of blood or interstitial fluid and for use in diagnostic testing or health monitoring. Tiny holes made by the needles induce a local change in pressure in the epidermis or dermis that forces interstitial fluid or blood into a collection device. Microneedle devices could enable testing and treatment to be delivered in underserved areas because they do not require costly equipment or a lot of training to administer.