In many states, yes — a dental hygienist can administer nitrous oxide (laughing gas), though it's far from universal.
Roughly 35 states permit hygienists to administer it, and several more allow them only to monitor a patient who is already sedated, while the rest don't permit either.
Training is always required where it's allowed, and the specifics are set by your state dental board.
The short answer
For a majority of the country, a dental hygienist can administer nitrous oxide with the proper training.
Reporting based on ADHA data puts it at roughly 35 states that allow administration, with around 8 more permitting hygienists only to monitor a patient the dentist has already sedated — and the remainder not permitting it at all.
Those counts are approximate and shift as states update their rules, so treat them as a general sense of the landscape rather than a precise tally.
Verify the current rule with your state board
Administering vs. monitoring — the key distinction
This question turns on a distinction that's easy to miss.
Administering means initiating and adjusting (titrating) the nitrous oxide yourself.
Monitoring means observing and maintaining a patient the dentist has already sedated, without starting it.
Some states let hygienists do both, some allow monitoring but not administering, and some allow neither.
So "can a hygienist do nitrous" really has two answers — check which one your state grants.
What training or permit you need
Where administering nitrous is allowed, it requires board-approved training — didactic instruction on the pharmacology and safety plus supervised clinical experience — and many states also require a specific permit on top of the RDH license.
This training is often offered alongside local-anesthesia certification, but the two are authorized separately, so completing one doesn't automatically grant the other.
Nitrous oxide and local anesthesia are separate questions
It's worth repeating because it trips people up: nitrous oxide and local anesthesia are governed independently.
A state may let a hygienist administer local anesthesia but only monitor nitrous, or the reverse.
When you're evaluating what you can do in a given state, check each function on its own rather than assuming permission for one implies the other.
How to confirm your state's rule
The ADHA publishes a state-by-state nitrous-oxide chart, and your state dental board publishes the practice act and any permit requirements.
If the two seem to disagree, the board is the authority.
Because the administer-versus-monitor line and the training requirements vary so much, verify the specifics for your exact state rather than generalizing.
This article is general information, not legal or clinical advice. Scope-of-practice and licensing rules vary by state and change over time — confirm current requirements with your state dental board.