Botulinum toxin (BoTox) injected into the muscle of the esophagus with endoscopic guidance works by paralyzing the muscle and allowing relaxation. Although it is easy to perform and can be initially effective in relieving symptoms of spastic esophageal disorders (such as achalasia or jackhammer esophagus), the effects are often temporary (typically on the order of weeks to months) and repeated injections lose efficacy. Furthermore, repeated injections can cause inflammation and scarring that can make more definitive treatments difficult or risky. As such, botulinum toxin should only be used for selected cases. Sometimes botulinum toxin is used as a therapeutic trial to see if paralysis of the muscle will relieve symptoms and indicate that a patient may be eligible for other treatment, such as POEM. Botox injection is generally very safe.