 Benzodiazepines, levo-dopacarbidopa, dopamine agonists, anticonvulsants, and opioids have been used with variable success, to treat RLS. Often, RLS patients treated with a benzodiazepine, over the course of several months, develop tolerance to the medication. Also, benzodiazepines can cause confusion or daytime sleepiness and may be addictive. Patients may also develop tolerance to levo-dopacarbidopa treatment. Because of the short half-life, symptoms may be suppressed for only the first part of the sleep period and then recur later during the night. Rebound has been reported. Worse yet, augmentation, the occurrence of RLS symptoms, often more severe than before treatment began, earlier in the day, may occur in up to 80 of RLS patients treated with levod-dopacarbidopa. Dopamine agonists, including pergolide, pramipexole, and ropinirole, are effective for some patients but not for others. Common side effects of these drugs include coryza, hypotension, and rash. Of the anticonvulsants, preliminary reports suggest that gabapentin, carbamazepine, and divalproex can suppress RLS symptoms in some patients, especially those with mild RLS. Side effects include sleepiness, ataxia, and weight gain. Opioid treatment for RLS has been described as effective but, aside from the stigma of taking controlled substances regularly, side effects may include nausea, sedation, constipation, and dysequilibrium. Iron supplementation is therapeutic in some patients with iron deficiency and RLS. 