Glossary
Sublingual administration
Last reviewed · Reviewed against Docto24 editorial standards
Absorption via the lining under the tongue — fast-onset, bypasses first-pass liver metabolism.
Sublingual administration delivers medication via absorption through the rich vascular bed under the tongue, bypassing first-pass hepatic metabolism. Onset is typically 15–45 minutes — faster than oral capsules (60–120 min) and slower than inhaled (within minutes). Bioavailability is intermediate and substantially more predictable than oral.
Sublingual is often confused with **oromucosal** (e.g. the THC:CBD spray formulation studied for MS spasticity), which delivers via the lining of the cheek and palate as well — practically similar but anatomically distinct.
In SA Section 21 prescribing, sublingual oils are a common route for daily-dose cannabinoid therapy where predictable, faster-than-oral onset matters but inhalation is undesirable. Patients are instructed to hold the dose under the tongue for 60–90 seconds before swallowing, to maximise sublingual absorption versus subsequent oral absorption.