No information is available as to specific results of an overdose of these products. The signs, symptoms and treatment described below are those of H₁ antihistamines and ephedrine overdose.

Symptoms

Should antihistamine effects predominate, central action constitutes the greatest danger. In the small child, symptoms include excitation, hallucination, ataxia, incoordination, tremors, flushed face and fever. Convulsions, fixed and dilated pupils, coma and death may occur in severe cases. In the adult, fever and flushing are uncommon; excitement leading to convulsions and postictal depression is often preceded by drowsiness and coma. Respiration is usually not seriously depressed; blood pressure is usually stable.

Should sympathomimetic symptoms predominate, central effects include restlessness, dizziness, tremor, hyperactive reflexes, talkativeness, irritability and insomnia. Cardiovascular and renal effects include difficulty in micturition, headache, flushing, palpitation, cardiac arrhythmias, hypertension with subsequent hypotension and circulatory collapse. Gastrointestinal effects include dry mouth, metallic taste, anorexia, nausea, vomiting, diarrhea and abdominal cramps.

Treatment

a) Evacuate stomach as condition warrants. Activated charcoal may be useful.
b) Maintain a nonstimulating environment.
c) Monitor cardiovascular status.
d) Do not give stimulants.
e) Reduce fever with cool sponging.
f) Support respiration.
g) Use sedatives or anticonvulsants to control CNS excitation and convulsions.
h) Physostigmine may reverse anticholinergic symptoms.
i) Ammonium chloride may acidify the urine to increase excretion of pseudoephedrine.
j) Further care is symptomatic and supportive.

Patients with hypersensitivity or idiosyncrasy to any of its ingredients. Sympathomimetic amines are contraindicated in patients with severe hypertension, severe coronary artery disease and patients on monoamine oxidase (MAO) inhibitor therapy. Antihistamines are contraindicated in patients with narrow-angle glaucoma, urinary retention, peptic ulcer and during an asthma attack.

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