Fentanyl citrate (Fentanyl)

Controlled Substances

Only midwives who have completed the “Opioids and Benzodiazepines: Safe Prescribing for Midwives” course may independently prescribe controlled substances.

Fentanyl citrate (Fentanyl) is a short-acting opioid which binds with receptors at many sites within the CNS, alters pain reception and increases the pain threshold. Fentanyl has no active metabolites and produces less sedation, nausea, and vomiting than morphine.

Indications and Clinical Use:

Midwives may only prescribe, order or administer fentanyl on their own authority for the purpose of pain relief in labour in hospital and not for any other purpose. Administration under any other circumstance must be on the order of a physician.


Fentanyl should not be used in the presence of uncorrected hypotension or hypovolemia, liver or kidney disease, respiratory compromise (e.g. severe asthma, cystic fibrosis), allergy or prior intolerable side effects to fentanyl (hallucinations) or a known hypersensitivity to fentanyl.

Fentanyl should not be used in the presence of an atypical or abnormal fetal heart rate or in the second stage of labour.

Fentanyl should not be administered within one hour of anticipated delivery.

Warnings and Precautions:

Fentanyl should be used with caution where there is a history of difficult intubation, if more than one dose of a longer-acting narcotic has already been received in labour, for preterm labour due to increased risk of respiratory depression in the neonate, in gestational hypertension due to increased sensitivity of hemodynamic effects of fentanyl or in those with a BMI greater than 35 as fentanyl is lipophilic and can lead to latent respiratory depression.

Opioids given near delivery may cause respiratory depression in the neonate at birth. The risk increases with increased cumulative doses. Prolonged use in gestation may cause neonatal withdrawal.

Naloxone should be readily available for administration. Physician consultation immediately after administration is required if Naloxone needs to be given.

Fentanyl may cause CNS depression which may impair physical or mental abilities. Use with caution in the presence of hepatic dysfunction, renal impairment, pre-existing respiratory compromise (hypoxia and/or hypercapnia), substance use or alcohol use.

One-to-one care must be provided. Monitor post administration according to hospital protocol or monitor vital signs, including respirations, and sedation scores for 30 minutes after IV fentanyl administration, then hourly for 4 hours.

Monitor oxygen saturation for 5-minute periods if bolus dose of 2 mcg/kg or total doses greater than 200 mcg/hr are used or if morphine or meperidine has been administered IM in the 3 hours preceding IV fentanyl administration. A physician should be consulted if oxygen saturations fall below 94%.


Human Data Suggest Risk

Opioid use during organogenesis is associated with a risk of congenital birth defects. Neonatal withdrawal is a risk after long-term exposure in pregnancy.


Category L2 – Limited Data- Probably Compatible

Fentanyl is considered suitable in lactation due to its shorter half-life and lack of an active metabolite. About 3-5% of the dose is known to enter milk. If this medication is used in lactation the lowest effective dose should be given for the shortest possible period of time. The neonate should also be monitored for signs of sedation, such as not waking up to feed at regular intervals.

Adverse Reactions:

Fentanyl may cause respiratory depression during labour and in the neonate at birth. Extra caution should be observed if fentanyl use continues for more than 5 hours or a total dose of 300 mcg has been administered. The larger the adult dose administered during labour, the greater the risk of neonatal respiratory depression. O2 saturation monitoring of the neonate is advised for at least 2 hours after birth whenever greater than 250 mcg has been given. As with any narcotic, watch for aspiration, drowsiness, hypotension and/or obtunded reflexes in addition to respiratory depression.

Dosage and Administration:

The recommended weight-based dose is 0.5 – 1 mcg/kg over 1-2 minutes waiting 5 minutes for effect and repeating every 10 minutes until satisfactory pain relief or a total maximum dose of 2 mcg/kg/hr (or 200 mcg/hr or 2-4 doses in 1 hour) has been given. Alternatively, with continuous O2 saturation monitoring, doses up to 1 mcg/kg (max. 100 mcg) can be given initially with repeat dosing every 15-20 minutes to a total of 200 mcg/hr (or 2 doses). Once a total dose of 3 mcg/kg has been administered, epidural or other alternate pain relief measures should be considered.

Add 100 micrograms (2 mL ampoule) to 8 mL normal saline to obtain 10 mL solution (concentration 10 mcg/mL) and give IV.


Fentanyl citrate may only be prescribed in hospital for the specific purposes listed here following hospital protocols.

Onset of Action:

3-5 minutes

Time to peak effect: 5-15 minutes


Adult – 2.4 hours

Neonate – 1.15 hours