As mentioned in the Introduction, drugs can either induce or reduce the frequency pf nightmares. Therefore, the most simple way to treat nightmares caused by drugs is to stop taking them, or to take alternative medications that do not interfere with the nervous system in the same way.
Medications are typically prescribed for sleep disorders in general. However, there has not been strong evidence suggesting that medication is necessary to treat all sleep disorders. Many of the drugs have been found to be effective in reducing the sleep-onset latency and number of night wakenings, but total time asleep may not be affected or the effect may be lost over time as the body develops a tolerance to it. Nevertheless, sedatives are frequently used by frustrated and desperate parents and their clinicians. Some specific examples of sedatives used are chloral hydrate, benzodiazapines, and even alcohol and sedative-containing cough medicines are used by some families. The problems associated with sedatives in children (besides noted side effects) are tolerance effects, withdrawal effects, and the fact that children who are not able to self-comfort (behaviorally) will often fight sleep despite the sedative, resulting in the occasional paradoxic response.
Drugs have been shown to be helpful for treating nightmares when children display or report symptoms of anxiety, fear, and stress which interfere with sleep. There are two classes of medication, benzodiazopines and tricyclic antidepressants, used to reduce or eliminate problems of this sort. These medications decrease deep delta sleep and arousals between sleep stages. However, Dahl (1992) suggests that these medications have limited benefit for this problem and that it can only be useful for short-term gains. The drawbacks to this medication are: 1) these medications may be simply masking the symptoms rather than treating the causes of the partial arousal, 2) tolerance effects occur frequently with these medications, 3) rebound effects can occur upon stopping the medication, resulting in severe increase in partial arousals, and 4) decreasing deep sleep in children by pharmacologic means may have detrimental effects, since growth hormone is primarily secreted during deep sleep. Therefore, Dahl (1992) suggests that identifying specific source of fears, anxieties, conditioned factors, and behavioral treatments may yield better long-term results. Often medication can be used to break cycles of insomnia for a temporary period, while simultaneous behavioral or relaxation therapy are used to prevent the recurrence of the nightmares.
Or check out the Different types of Nightmares