Naloxone Guide: Emergency Opioid Overdose Reversal
Naloxone is an opioid antagonist that can reverse an opioid overdose by helping restore breathing. It is available as a nasal spray or injection and is often given by family members or bystanders while emergency help is on the way. Healthcare professionals may also prescribe it as part of treatment for opioid use disorder.
If an opioid overdose is suspected, give naloxone promptly and call emergency services right away. Naloxone can be lifesaving, but its effects may wear off before the opioid does, so medical care is still needed.
Key facts at a glance
- ATC
- V03AB15
- Generic
- Naloxone
- Class
- opioid-antagonist
- Brands
- Narcan
- Availability
- behind_counter
- Pregnancy
- B
- Lactation
- caution
- Half-life (h)
- 2
- Onset (min)
- 2
- Duration (h)
- 1
- Routes
- im, intranasal, iv
- Forms
- injection, nasal-spray
- Regions
- CN, US, EU, JP
- Monitoring
- respiratory-rate
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 0.4mg to 2mg
- Maximum
- consult physician
- Frequency
- every 2 to 3 minutes as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 0.01 mg per kg body weight
- Maximum
- consult physician
- Frequency
- every 2 to 3 minutes as needed, up to 2mg per dose
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 0.4mg to 1mg
- Maximum
- consult physician
- Frequency
- every 2 to 3 minutes as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
8 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks; use only in life-threatening opioid overdose situations
regular fetal monitoring
Use with caution and monitor for adverse effects.
pregnancy
third trimesteruse lowest effective dose
use only when benefits clearly outweigh risks; consider effects on fetus
continuous fetal monitoring
Use with caution and monitor for adverse effects.
lactation
breastfeedingno adjustment needed
compatible with breastfeeding; minimal breast milk transfer expected
none required
geriatric
elderlyreduce initial dose by 50%
use with caution; start with lower doses; monitor for cardiovascular events
close monitoring of blood pressure, heart rate, and respiratory status
Use with caution and monitor for adverse effects.
pediatric_age
childrenweight-based dosing required
use pediatric formulation; initial dose 0.01 mg/kg; may repeat every 2-3 minutes
continuous cardiorespiratory monitoring
Use with caution and monitor for adverse effects.
pediatric_age
neonatesweight-based dosing required
use in neonatal opioid withdrawal syndrome; initial dose 0.01 mg/kg IV/IM/SC; titrate carefully
continuous monitoring of vital signs; observe for withdrawal symptoms
Use with caution and monitor for adverse effects.
renal_impairment
severeuse with caution; no specific dose adjustment established
use lowest effective dose; monitor renal function
monitor renal function and respiratory status
Use with caution and monitor for adverse effects.
hepatic_impairment
severeuse with caution; no specific dose adjustment established
use lowest effective dose; monitor for prolonged effect
monitor hepatic function and respiratory status
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA approval year
Initial FDA approval for opioid overdose reversal
Drug class
ATC classification N07AB01 - Opioid antagonists
Primary indication
Emergency treatment for suspected opioid overdose
Available formulations
Narcan nasal spray approved 2015, injectable available since 1971
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy