<unk>  is one of the most commonly misused over the counter drugs in the United States. In cases of extreme overdose, if not treated in time, acute<unk>  poisoning may have serious and potentially fatal consequences. Overdose symptoms may include: * Euphoria or dysphoria * Hallucinations (auditory, visual, etc.) * Heart palpitations * Extreme drowsiness * Severe dizziness * Abnormal speech (inaudibility, forced speech, etc.) * Flushed skin * Severe mouth and throat dryness * Tremors * Seizures * Inability to urinate * Vomiting * Acute megacolon * Motor disturbances * Anxiety/nervousness * Disorientation * Abdominal pain * Delirium * Coma * Death Acute poisoning can be fatal, leading to cardiovascular collapse and death in 2–18 hours, and in general is treated using a symptomatic and supportive approach. Diagnosis of toxicity is based on history and clinical presentation, and in general specific levels are not useful. Several levels of evidence strongly indicate<unk>  (similar to chlorpheniramine) can block the delayed rectifier potassium channel and, as a consequence, prolong the QT interval, leading to cardiac arrhythmias such as torsades de pointes. No specific antidote for<unk>  toxicity is known, but the anticholinergic syndrome has been treated with physostigmine for severe delirium or tachycardia. Benzodiazepines may be administered to decrease the likelihood of psychosis, agitation, and seizures in people who are prone to these symptoms.
Diphenhydramine
Olopatadine
Ephedrine
Pseudoephedrine
Meclizine
Lofepramine
Dezocine
Molsidomine