Acetaminophen: Substrate (minor) of CYP1A2, 2A6, 2C8/9, 2D6, 2E1, 3A4; Inhibits CYP3A4 (weak)
Dextromethorphan: Substrate of CYP2B6 (minor), 2C8/9 (minor), 2C19 (minor), 2D6 (major), 2E1 (minor), 3A4 (minor); Inhibits CYP2D6 (weak)
Also see individual agents.
Oral: Analgesic: Based on acetaminophen component:
Children: 10-15 mg/kg/dose every 4-6 hours as needed; do not exceed 5 doses/24 hours
Adults: 325-650 mg every 4-7 hours as needed; do not exceed 4 g/day
Cough suppressant: Based on dextromethorphan component:
Children 6-12 years: 15 mg every 6-8 hours; do not exceed 60 mg/24 hours
Children >12 years and Adults: 10-20 mg every 4-8 hours or 30 mg every 8 hours; do not exceed 120 mg/24 hours
Decongestant: Based on pseudoephedrine component:
Children:
2-6 years: 15 mg every 4 hours (maximum: 90 mg/24 hours)
6-12 years: 30 mg every 4 hours (maximum: 180 mg/24 hours)
Children >12 years and Adults: 60 mg every 4 hours (maximum: 360 mg/24 hours)
Product labeling:
Alka-Seltzer Plus Cold and Flu Liqui-Gels:
Children 6-12 years: 1 dose every 4 hours (maximum: 4 doses/24 hours)
Children >12 years and Adults: 2 dose every 4 hours (maximum: 4 doses/24 hours)
Infants' Tylenol Cold Plus Cough Concentrated Drops: Children 2-3 years (24-55 lb): 2 dropperfuls every 4-6 hours (maximum: 4 doses/24 hours)
Sudafed Severe Cold, Thera-Flu Non-Drowsy Maximum Strength (gelcap), Tylenol Flu Non-Drowsy Maximum Strength: Children >12 years and Adults: 2 doses every 6 hours (maximum: 8 doses/24 hours)
Tylenol Cold Non-Drowsy:
Children 6-11 years: 1 dose every 6 hours (maximum: 4 doses/24 hours)
Children 
12 years and Adults: 2 doses every 6 hours (maximum: 8 doses/24 hours)
Thera-Flu Non-Drowsy Maximum Strength: Children >12 years and Adults: 1 packet dissolved in hot water every 6 hours (maximum: 4 packets/24 hours)
[DSC] = Discontinued product Caplet:
Contac Severe Cold and Flu/Non-Drowsy, Sudafed Severe Cold, Tylenol Cold Non-Drowsy: Acetaminophen 325 mg, dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg
Comtrex Non-Drowsy Cold and Cough Relief: Acetaminophen 500 mg, dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg [contains benzoic acid]
Thera-Flu Severe Cold Non-Drowsy: Acetaminophen 500 mg, dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg [contains lactose] [DSC]
Tylenol Cold Day Non-Drowsy: Acetaminophen 325 mg dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg
Capsule, liquid
Alka-Seltzer Plus Flu Liqui-Gels: Acetaminophen 325 mg, dextromethorphan hydrobromide 10 mg, and pseudoephedrine hydrochloride 30 mg
Vicks DayQuil Multi-Symptom Cold and Flu: Acetaminophen 250 mg, dextromethorphan hydrobromide 10 mg, and pseudoephedrine hydrochloride 30 mg
Gelcap:
Tylenol Cold Day Non-Drowsy: Acetaminophen 325 mg dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg [contains benzyl alcohol]
Tylenol Flu Non-Drowsy Maximum Strength: Acetaminophen 500 mg, dextromethorphan hydrobromide 15 mg, and pseudoephedrine hydrochloride 30 mg
Liquid:
Triaminic Cough and Sore Throat Formula: Acetaminophen 160 mg, dextromethorphan hydrobromide 7.5 mg, and pseudoephedrine hydrochloride 15 mg per 5 mL (120 mL, 240 mL) [contains benzoic acid; grape flavor]
Vicks DayQuil Multi-Symptom Cold and Flu: Acetaminophen 325 mg, dextromethorphan hydrobromide 10 mg, and pseudoephedrine hydrochloride 30 mg per 15 mL (175 mL)
Powder for oral solution [packet] (Thera-Flu Severe Cold Non-Drowsy): Acetaminophen 1000 mg, dextromethorphan hydrobromide 30 mg, and pseudoephedrine hydrochloride 60 mg [contains phenylalanine 17 mg/packet; lemon flavor] [DSC]
Suspension, oral drops (Infants' Tylenol Cold Plus Cough Concentrated Drops): Acetaminophen 160 mg, dextromethorphan hydrobromide 5 mg, and pseudoephedrine hydrochloride 15 mg per 1.6 mL (15 mL) [1.6 mL = 2 dropperfuls] [cherry flavor]