TABLE 1.

Classes of drugs and their associated adverse effects

Active ingredient class	Example(s)	Possible adverse effect(s)
Decongestants	Pseudoephedrine, phenylephrinse	Tachycardia, restlessness, insomnia, anxiety, tremors, hypertension, irritability, anorexia, lethargy, headaches, dysrhythmias, hallucinations, dystonic reactions, seizures.
Antitussives	Dextromethorphan	Constipation, dizziness, drowsiness, nausea, vomiting, respiratory ataxia. depression, apnea, palpitations, possible serotonin syndromewith SSRIs.
Antihistamines	Diphenhydramine, chlorpheniramine, brompheniramine	Drowsiness/sedation, dizziness, headache, dry mouth, dry eyes, paradoxic excitability, respiratory depression, hallucinations, tachycardia, arrhythmias, blurred vision
Expectorants	Guaifenesin	Nausea, diarrhea, dizziness, headache but generally well tolerated.

SSRI Selective serotonin reuptake inhibitors