The shelves in David Julius’s lab at the University of California, San Francisco, could be confused with those in a traditional herbal medicine shop. They hold bottles labeled “menthol extract” and “capsaicin,” the substance that gives heat to hot peppers. The eye-watering scents of Szechuan peppers, wasabi, and herbs waft through the air. They might seem unlikely tools for one of the world’s most advanced neurobiology pain research centers, but Julius uses this trove of natural ingredients to probe the molecular world of pain.

Neurologists and pain specialists long struggled to prove that controlling pain can speed a patient’s recovery after surgery or an injury and that people with chronic pain have a genuine malady that’s not “all in their head.” Today the biomedical world recognizes that pain is a real and pressing health care issue that needs improved diagnosis and more effective treatments. Until about 15 years ago, though, researchers could study pain based only on patient behavior and subjective responses to questions about “where” and “how much” it hurts. As a result of emerging molecular findings, new pain medications and diagnostic tools are being developed.

Illustration by Sam Green