The SL medical abbreviation means sublingual, so a medicine marked SL is placed under the tongue and left to dissolve rather than swallowed. The word comes from the Latin sub, under, and lingua, tongue.
The area under the tongue has a thin lining and many small blood vessels, so some medicines pass into the bloodstream there within minutes. That speed is why SL is the route for certain medicines meant to act quickly, and why the instruction to let a tablet dissolve, not chew or swallow it, matters for how well it works.
At a glance
Stands for
Sublingual, under the tongueWord roots
Sub (under) plus lingua (tongue)Written as
SL, sl, sublingWhere you see it
Prescriptions, hospital orders, emergency protocols, medication labelsForms
Tablets, films and sprays made for under the tongueDo not confuse with
Buccal (inside the cheek) and ODT (dissolves on the tongue)
What the SL medical abbreviation means for a dose
SL is a route, like PO or IV. It tells the person giving the medicine where it goes, not how much or how often. A sublingual tablet or film is placed under the tongue, the mouth stays closed, and the medicine is absorbed through the tissue there.
Medicine absorbed this way enters the blood directly and skips the first trip through the stomach and liver. For some drugs, that means a faster effect and more of the dose reaching the body. If a sublingual tablet is swallowed instead, it may work more slowly or less well, which is why the label stresses the method.
Decoding a sublingual order
The best known SL medicine is nitroglycerin for chest pain. Its order is a good example of how several short terms combine.
| Piece | Meaning |
|---|---|
| Nitroglycerin 0.4 mg | The medicine and the amount in each tablet |
| SL | Under the tongue |
| q5min x 3 | Every 5 minutes, up to 3 doses |
| PRN chest pain | Only when chest pain occurs |
This line shows the format only. Instructions for when to call emergency services are part of a real nitroglycerin prescription and are set by the prescriber.
Nurse's note: "Pt c/o chest pressure 6/10, NTG 0.4 mg SL given, pressure 2/10 after 5 min, provider notified." The nurse gave one sublingual nitroglycerin tablet and recorded the response.
Medicines often given SL
Only certain medicines are made to work under the tongue. Common examples include:
- Nitroglycerin: tablets or spray for angina, the chest pain linked to reduced blood flow to the heart.
- Buprenorphine: tablets and films used in treatment for opioid use disorder.
- Some hormone and sleep products: certain forms are designed to dissolve under the tongue.
In hospitals, a clinician may also order a regular tablet to be given SL when a patient cannot swallow, but only when the drug is known to absorb that way. Patients should not switch routes on their own.
SL versus buccal, ODT and PO
Four ways of taking medicine by the mouth get blurred together often.
| Term | Where the medicine goes | Swallowed? |
|---|---|---|
| SL | Under the tongue | No, absorbed in the mouth |
| Buccal | Between the cheek and gum | No, absorbed in the mouth |
| ODT | On top of the tongue, where it breaks apart | Yes, mostly swallowed with saliva |
| PO | Swallowed whole | Yes |
The Joint Commission has not banned SL, though in handwriting it can blur with other short route terms, so many electronic systems print under the tongue on labels.
Tips for taking a sublingual medicine
Your pharmacist will give exact steps for your product, but common points include:
- Place the tablet or film under the tongue and close your mouth.
- Do not chew, suck or swallow it until it has dissolved.
- Avoid eating, drinking or smoking until it is fully absorbed, unless told otherwise.
- Some products cause a brief tingling or burning, which can be normal.
Store tablets as the label directs. Some sublingual products lose strength if exposed to heat, light or air.
SL nursing abbreviation in practice
Nursing and pharmacy students learn SL with the other route abbreviations and document it exactly as ordered. When giving an SL dose, nurses check that the mouth is moist enough to dissolve the tablet and watch for expected effects, such as a drop in blood pressure after nitroglycerin. The full set of route and timing shorthand lives in the prescription abbreviations section.
The examples here describe the route in general. How and when to use your own under the tongue medicine, and what to do if it does not help, is something to settle with your prescriber or pharmacist.
Frequently asked questions
What does SL mean on a prescription?
SL means sublingual, so the medicine goes under the tongue and dissolves there. It should not be swallowed whole unless the label says so.
What is the medical abbreviation for sublingual?
The standard abbreviation is SL. On a bottle, the pharmacy normally prints under the tongue in words instead.
Why do some medicines go under the tongue?
The tissue under the tongue absorbs some drugs quickly into the blood. That route can work faster than swallowing and skips the first pass through the liver.
Is SL the same as ODT?
No. An SL tablet stays under the tongue and is absorbed there. An ODT dissolves on top of the tongue and is mostly swallowed with saliva.
Can I swallow an SL tablet?
Sublingual tablets are designed to be absorbed in the mouth, so swallowing may weaken or slow the effect. Ask your pharmacist about your specific product.