This is a group of medications that are used as minor tranquilizers to help calm patients who have fears and nervousness that interfere with the their enjoyment of life. Benzodiazepines, a large group of anti-anxiety agents of which Valium, Ativan, Tranxene, and Xanax are just a few, represent most commonly used anti-anxiety agents. These medications can also aid insomnia. They can pose a risk of habituation and dependency and have other side effects such as depression. Like all drugs, the benefits of the medication must be weighed against their possible complications. When used short-term they can be most helpful. For example, people with claustrophobia cannot bear to lie still in confined spaces during an MRI examination. To combat this, severe anti-anxiety agents are given an hour before the MRI, and this usually allows the patient to tolerate the test.  Similarly, patients with needle phobia often cannot tolerate undergoing an epidural injection or other spinal procedure without first being pre-medicated with an anti-anxiety agent. These agents can also be useful in the treatment of muscle spasms.