What does SL mean on a prescription?
SL means sublingual — place the tablet or spray under your tongue and let it dissolve. Do not swallow it whole.
- Means:
- under the tongue
- From:
- sub lingua
- Type:
- How to take it
- Also written:
- sl, s.l., SL, sublingual
What it means in practice
Medicine absorbed under the tongue passes straight into the bloodstream, bypassing the stomach and liver, so it acts within minutes. That is why glyceryl trinitrate for angina is given SL. Swallowing an SL tablet largely wastes the dose.
Example on a prescription
GTN 400 mcg 1 spray SL PRN chest pain
Spray one 400 mcg dose under the tongue when you have chest pain, following the instructions you were given about repeat doses and when to call for help.
Commonly confused with
- POPO tablets are swallowed. SL tablets must dissolve under the tongue instead.
Worth knowing
Swallowing a sublingual tablet instead of letting it dissolve can leave you without the effect you need. For angina sprays, follow the specific advice you were given about when to seek emergency help.
Frequently asked questions
What does SL mean on a prescription?
Sublingual — put it under your tongue and let it dissolve rather than swallowing.
Why is sublingual faster?
The lining under the tongue absorbs the medicine directly into the bloodstream, so it skips the stomach and the liver's first pass.
Related abbreviations
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This page explains prescription notation for general information. It is not medical advice and does not replace your prescriber or pharmacist. If a label is unclear or differs from what you were told, check with your pharmacy before taking the medicine.