 Your nose will start running, hurting, and sneezing. Capsaicin is the burning component of hot peppers. Why would you do such an experiment? Anyone who's handled the compound in the lab knows that if it gets up your nose, it causes an intense burning sensation. However, this phenomenon has not been formally investigated. Therefore, it appeared worthwhile to study the effects produced by the topical application of capsaicin in the human nose. It therefore appeared worthwhile because it never had been done before? OK. So they took some medical students, dripped some in their nose, and they started sneezing, burning, and snotting. Describing the pain is like 8 or 9 on a scale of 1 to 10. No surprise, but here's the interesting part. What do you think happened when they repeated the experiment the next day? You'd think they might be sensitized to it. You know, still all irritated, and so it might hurt even worse. But no, it hurt less. Then they did it again the next day, and the next. By day 5, it hardly hurt at all. They didn't even get a runny nose, no sneezing. Came back the next week, day 10, and still nothing. Sheesh, were they like permanently numbed? No, after a month or so, the desensitization wore off, and they were back in agony whenever they tried rubbing it in their nose. What the researchers think is happening is that the pain fibers, the nerves that carry pain sensation, dumped so much of the pain neurotransmitter called substance P that they ran out. Day after day of this, the nerves had exhausted their stores and could no longer transmit pain messages until they made more substance P from scratch, which takes a couple weeks. This gave researchers an idea. There's a rare headache syndrome called cluster headache. It's been described as one of the worst pains humans experience. Few, if any, medical disorders are more painful. It's nicknamed the suicide headache, because patients often consider taking or have taken their lives over it. It's thought to be caused by arterial dilation putting pressure on the trigeminal nerve in the face. Treatments involve everything from nerve blocks to Botox to surgery, but hey, that same nerve goes down to the nose. What if we caused the whole nerve to dump all its substance P? Preventive effect of repeated nasal applications of capsaicin in cluster headache. Same as before, capsaicin in the nose, and by day 5 they could hardly feel it anymore. Note though that these were cluster headache sufferers, and so what was rated as an 8 or 9 on the pain scale by the wimpy medical students was like maybe a 3 or 4 by those used to the violence of the cluster headache attacks. Having achieved desensitization, what happened to their headaches? Well cluster headaches are one-sided headaches. You only get pain on one side of your head. So those who had rubbed capsaicin in the opposite nostril on the wrong side of the head, nothing happened. They started out having like 40 attacks a day, and a month later the headaches were still going strong. But those that rubbed the capsaicin in the nostril from the side of the head where the headaches were cut the average number of attacks in half. And in fact half the patients were cured. The cluster headaches were gone completely. All in all, 80% responded. At least equal, if not better, than all the current therapies out there.