How the dose is calculated
Fentanyl is dosed per single administration by weight — doses are in milligrams here for consistency with the shared engine, but note fentanyl is almost always prescribed and labelled in micrograms (mcg); 0.001 mg = 1 mcg.
Typical dosing by route
| Route | Dose | Frequency | Max single dose |
|---|---|---|---|
| IV | 1 mcg/kg | q2-3min prn to effect | 50 mcg |
| Intranasal | 1.5 mcg/kg | single dose, split both nostrils | 100 mcg |
Fentanyl has a rapid onset (1-2 min IV) and short duration, making it well suited for brief painful procedures. Rapid IV push can cause chest wall rigidity, especially at higher doses — give slowly.
Clinical use
- Widely used for procedural sedation/analgesia (fracture reduction, laceration repair) and rapid-onset pain control given its fast onset and short half-life.
- Intranasal fentanyl is particularly useful in children or when IV access isn't yet available, providing effective analgesia without a needle.
- Has less histamine release than morphine, making it a preferred opioid in haemodynamically unstable patients.
Frequently asked questions
What is fentanyl used for?
Rapid-onset analgesia and procedural sedation — its fast onset and short duration make it well suited for brief painful procedures and acute pain control.
Why is intranasal fentanyl useful in children?
It provides effective, fast-onset analgesia without needing IV access, which is especially valuable in a distressed child with a painful injury before a cannula can be placed.
What is chest wall rigidity with fentanyl?
A rare but serious complication of rapid IV fentanyl administration (especially at higher doses) causing stiffness of the chest wall that can impair ventilation — giving the dose slowly over 1-2 minutes reduces this risk.
References
- American College of Emergency Physicians. Clinical Policy: Procedural Sedation and Analgesia in the Emergency Department.
- British National Formulary for Children (BNFc) — Fentanyl.