Contraindications
Lorazepam should be avoided in people with:

Allergy or hypersensitivity – Past hypersensitivity or allergy to lorazepam, to any benzodiazepine, or to any of the ingredients in lorazepam tablets or injections
Respiratory failure – Benzodiazepines, including lorazepam, may depress central nervous system respiratory drive and are contraindicated in severe respiratory failure. An example would be the inappropriate use to relieve anxiety associated with acute severe asthma. The anxiolytic effects may also be detrimental to a persons willingness and ability to fight for breath. However, if mechanical ventilation becomes necessary, lorazepam may be used to facilitate deep sedation. Acute intoxication – Lorazepam may interact synergistically with the effects of alcohol, narcotics, or other psychoactive substances. It should, therefore, not be administered to a drunk or intoxicated person. Ataxia – This is a neurological clinical sign, consisting of unsteady and clumsy motion of the limbs and torso, due to the failure of gross muscle movement coordination, most evident on standing and walking. It is the classic way in which acute alcohol intoxication may affect a person. Benzodiazepines should not be administered to people already-ataxic. Acute narrow-angle glaucoma – Lorazepam has pupil-dilating effects, which may further interfere with the drainage of aqueous humor from the anterior chamber of the eye, thus worsening narrow-angle glaucoma. Sleep apnea – Sleep apnea may be worsened by lorazepams central nervous system depressant effects. It may further reduce the persons ability to protect his or her airway during sleep.
Acute delirium is sometimes treated with lorazepam, but as it can cause paradoxical effects, it is preferably given together with haloperidol. Lorazepam is absorbed relatively slowly if given intramuscularly, a common route in restraint situations. Other
Catatonia with inability to speak is responsive to lorazepam. Symptoms may recur and treatment for some days may be necessary. Catatonia due to abrupt or overly rapid withdrawal from benzodiazepines, as part of the benzodiazepine withdrawal syndrome, should also respond to lorazepam treatment. As lorazepam can have paradoxical effects, haloperidol is sometimes given at the same time.It is sometimes used in chemotherapy in addition to medications used to treat nausea and vomiting, i.e. nausea and vomiting caused or worsened by psychological sensitization to the thought of being sick. Adverse effects
Many beneficial effects of lorazepam (e.g., sedative, muscle relaxant, anti-anxiety, and amnesic effects) may become adverse effects when unwanted. Adverse effects can include sedation and low blood pressure; the effects of lorazepam are increased in combination with other CNS depressant drugs. Other adverse effects include confusion, ataxia, inhibiting the formation of new memories, pupil constriction and hangover effects. With long-term benzodiazepine use it is unclear whether cognitive impairments fully return to normal after stopping lorazepam use; cognitive deficits persist for at least six months after withdrawal, but longer than six months may be required for recovery of cognitive function. Lorazepam appears to have more profound adverse effects on memory than other benzodiazepines; it impairs both explicit and implicit memory. In the elderly, falls may occur as a result of benzodiazepines.