Acting strange after trying to ‘get numb’

On mental status examination, Mr. L has an appropriate appearance and appears to be his stated age. He shows good eye con­tact and is cooperative. Muscle tone and gait are within normal limits. He has no abnormal movements. Speech, thought processes, and associations are normal. He denies auditory hallucinations, visual hallucinations, suicidal ideation (although he presented with a prob­able suicide attempt), or homicidal ideation. No delusions are elicited.

Mr. L shows poor judgment about his drug use and situation. He demonstrates limited insight, because he says his only goal is to get out of the hospital. He is alert, awake, and oriented to person, place, and time. He shows no memory or knowledge impairment. He appears euthymic with an inappropriate and constricted affect. On neurologic exam, he had mild tremors in his hands. The authors’ observationsTreatment for diphenhydramine over­dose should begin quickly to prevent life-threatening effects and reduce the risk for mortality. The toxin can be removed from the patient’s GI tract with activated char­coal or gastric lavage if the patient presents within 1 hour of ingesting the substance. Administering IV fluids will prevent dehy­dration. Cardiac functioning is monitored and benzodiazepines could be adminis­tered to manage seizures.

Key elements of a toxicologic physical examination include:
• eyes: pupillary size, symmetry, and response to light (vertical or horizontal nystagmus)
• oropharynx: moist or dry mucous membranes, presence or absence of the gag reflex, distinctive odors
• abdomen: presence or absence and quality of bowel sounds
• skin: warm and dry, warm and sweaty, or cool
• neurologic: level of consciousness and mental status, presence of tremors, seizures, or other movement disorders, presence or absence and quality of deep tendon reflexes.⁷

If a child or adolescent patient cannot communicate how much of a drug he (she) has ingested, questions to ask parents or other informants include:
• Was the medication purchased recently, and if so was the bottle or box full before the patient took the pills?
• If the medication was not new, how many pills were in the bottle before the patient got to it?
• If the medication was prescribed, how many pills were originally prescribed, when was the medication prescribed, and how many pills were already taken prior to the patient getting to the bottle?
• How many pills were left in the bottle?
• How many pills were seen around the area where the patient was found?
• How many pills were found in the patient’s mouth?⁷

Recommendations
It is well known that OTC medication abuse is a growing medical problem (Table 2). Antihistamines, including diphenhydramine, are readily available to minors and adults. Because of the powerful sedating effects of antihistamines, many adolescent health practitioners give them to patients who have insomnia as a sleep aid.⁸ As in our case, antihistamines are used recreationally for their hallucinogenic effects, at dosages of 300 to 700 mg.⁹ Severe symptoms of toxicity, such as delirium and psychosis, seizures, and coma, occur at dosages ≥1,000 mg.⁹

With growing abuse of these medications, we aim to encourage detailed history taking about abuse of OTC drugs, especially diphenhydramine in adolescent patients.

Outcome Improvement, discharge
Mr. L is given a dual diagnosis of diphenhydramine-induced psychotic disorder with
hallucinations and diphenhydramine-induced depressive disorder, both with onset during intoxication. He also is given a provisional diagnosis of psychotic disorder not otherwise specified and major depressive disorder. Last, he is given a diagnosis of Cannabis dependence with physiological dependence, MDMA abuse, hydrocodone abuse, and Robitussin abuse.

Mr. L is maintained on fluoxetine, 40 mg/d, and risperidone, 1 mg at bedtime and 0.5 mg in the morning. He receives milieu, individual, group, recreational, and medical therapy while in the hospital. Symptoms abate and he is discharged with a plan to follow up with outpatient providers.

Bottom Line
Abuse of over-the-counter (OTC) drugs, such as diphenhydramine, among youths is a growing problem. Remember to question adolescents who appear intoxicated or to have overdosed not only about abuse of alcohol and illicit substances but also of common—and easily and legally accessible—OTC drugs.

Related Resources
• Carr BC. Efficacy, abuse, and toxicity of over-the-counter cough and cold medicines in the pediatric population. Curr Opin Pediatr. 2006;18(2):184-188.
• Thomas A, Nallur DG, Jones N, et al. Diphenhydramine abuse and detoxification: a brief review and case report. J Psychopharmacol. 2009;23(1):101-105.

Drug Brand Names
Diazepam • Valium Hydrocodone • Vicodin
Diphenhydramine • Benadryl Risperidone • Risperdal
Fluoxetine • Prozac

Disclosures
The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.