Capzasin works by using the anti-inflammatory power of capsaicin, which is derived from hot peppers. It's packaged with a hands-free applicator, which is a must because did I mention the active ingredient is derived from hot peppers? You really don't want to get this ointment on your hands if you can avoid it. Capsaicin works quickly and effectively at reducing muscle pain, but woe betide you if you should touch the ointment and then touch a mucus membrane. Ouch does even begin to cover it. It also tends to redden the site of application when you take a shower later (bath not recommended if you have this on your body). And it smells like tabasco. There are times when it's better than other options though. I always keep a tube around.