Routes, Dosage Forms, and Average Onsets of Action

I am frequently asked by healthcare professionals (i.e. physicians, physician assistants, nurses, nurse practitioners, pharmacists) about Routes, Dosage Forms, and the Average Onsets of Action 1. When it comes to designing and engineering a personal medicated product for a patient, choosing the correct dosage form and route is critical: age, weight, hospice, pediatric, women, men, etc. — each variable is taken into consideration. Plus, I wanted to play with a new way to display the HTML element Description List using flexbox. Resize your browser window to see the magic happen! (Reader says, “Chill out Eric, it’s just flexbox. I don’t think you need the exclamation point.”)

Intravenous (IV)
Dosage Form: Aqueous solutions, emulsions
Onset of Action: Within 60 seconds
Intramuscular (IM)
Dosage Form: Aqueous solutions, oily solutions, suspensions
Onset of Action: 15 to 30 minutes for aqueous solutions
Subcutaneous (Sub-Q)
Dosage Form: Aqueous solutions, suspensions, implants
Onset of Action: 15 to 60 minutes for aqueous solutions
Dosage Form: Tablets, solutions, aerosols
Onset of Action: 1 to 3 minutes
Dosage Form: Tablets, lozenges (troches), chewing gum
Onset of Action: 2 to 3 minutes
Dosage Form: Tablets, solutions, suspensions
Onset of Action: 30 to 60 minutes for immediate release (IR) dosage forms
Dosage Form: Suppositories, ointment, creams, solutions, suspensions, foams
Onset of Action: 30 to 60 minutes
Dosage Form: Inserts, creams, gels, tablets, rings
Onset of Action: Slow for systemic effects
Skin (transdermal)
Dosage Form: Patches, ointments, gels
Onset of Action: 1 to 4 hours
Dosage Form: Aerosolized solutions or suspensions
Onset of Action: Within 10 minutes
Dosage Form: Aerosolized solutions, suspensions, or powders
Onset of Action: Within 5 minutes


  1. Adapted from Chambers Fox S. Remington Education: Pharmaceutics. Fairford, UK; Pharmaceutical Press: 2014.