Butethal is a sedative and a hypnotic drug indicated for the treatment of severe intractable insomnia. It acts on receptors in the brain (GABA A receptors) causing the release of the chemical GABA. This chemical inhibits certain areas of the brain resulting in sleepiness. Common side effects are: drowsiness, sedation, unsteadiness, vertigo and inco- ordination. Also, hangover effect, paradoxical excitement, confusion, memory defects and skin rashes. Interactions may occur with the following: adrenocorticoids (cortisone-like medicine), anticoagulants (blood thinners), carbamazepine, corticotropin (barbiturates may decrease the effects of these medicines), central nervous system (CNS) depressants (using these medicines with barbiturates may result in increased CNS depressant effects), divalproex sodium, valproic acid (using these medicines with barbiturates may change the amount of either medicine that you need to take), and oral contraceptives containing estrogens (barbiturates may decrease the effectiveness of these oral contraceptives, and you may need to change to a different type of birth control).