Naloxone is an opioid antagonist that can temporarily reverse opioid-induced respiratory depression. It has no effect on a person who has not taken opioids and should not delay emergency care.
AddictionInfo Editorial Team 8 minute read Evidence checked September 4, 2026
Suspected overdose is an emergency
Call your local emergency number now. If opioids may be involved and naloxone is available, give it according to its instructions, stay with the person, and be prepared to give another dose if they do not respond. See crisis contacts.
Clinical overview
Quick answer
Naloxone is an opioid antagonist that can temporarily reverse opioid-induced respiratory depression. It has no effect on a person who has not taken opioids and should not delay emergency care.
Evidence checked4 September 2026
Editorial standardReviewed against current clinical and public-health guidance
ScopeEducation only—not diagnosis or individual medical advice
What this means
Overdose response includes recognising abnormal breathing, calling emergency services, giving naloxone, supporting breathing or CPR as trained, and staying with the person because effects can return.
Key distinctions
Follow local device instructions
more than one dose may be needed
recovery position is appropriate when normal breathing returns and spinal injury is not suspected.
Signs and patterns clinicians assess
A clinician looks at the pattern over time, its severity, the person’s baseline, and the consequences—not at one isolated behaviour. Relevant features can include:
craving, loss of control, or use outside the prescribed plan
sedation, pinpoint pupils, slowed breathing, constipation, or repeated intoxication
continued use despite overdose, health, relationship, financial, or legal harms
withdrawal symptoms such as aches, sweating, diarrhoea, nausea, anxiety, and insomnia
return to use after detox or abstinence, when reduced tolerance can sharply increase overdose risk
These signs are not a self-diagnosis. Intoxication, withdrawal, prescribed use, pain, sleep disorders, and mental-health conditions can overlap, so assessment should establish what is happening and what is immediately unsafe.
Health and safety risks
Risk depends on the substance or medicine, route, dose, frequency, combinations, physical health, mental health, and environment. Important concerns include:
fatal respiratory depression and overdose
unpredictable potency, especially with illicit fentanyl and mixed drug supplies
infection and vascular injury when drugs are injected
dangerous sedation when combined with alcohol, benzodiazepines, gabapentinoids, or other depressants
loss of tolerance after detoxification, incarceration, hospitalisation, or residential treatment
Assessment and treatment
Good care starts with consent, dignity, and a clear assessment of immediate risk. Treatment intensity should be matched to clinical need rather than to marketing labels or a fixed programme length.
rapid access to an opioid-use assessment and overdose-prevention plan
naloxone access and training for the person and people around them
evidence-based medication such as buprenorphine or methadone where available and appropriate
management of pain, mental health, infection risk, housing, and social needs
continuing care rather than detoxification as a stand-alone intervention
Recovery plans should state who is responsible for medication, crisis support, physical-health follow-up, family communication, and continuing care. A lapse should trigger prompt reassessment and additional support—not abandonment or shame.
When to seek urgent help
Suspect opioid overdose when a person is unresponsive, breathing slowly or not at all, making choking or gurgling sounds, or has blue/grey lips or fingertips. Call emergency services, give naloxone if available, provide rescue breathing or CPR as trained, and stay until help arrives.
Questions to ask a treatment provider
Who performs the medical and psychiatric assessment, and what are their current qualifications and registrations?
How is withdrawal, overdose, suicide risk, medication, and physical illness managed?
Which treatments are offered for this specific condition, and what evidence supports them?
What happens if symptoms worsen or hospital care is required?
How are outcomes, complaints, safeguarding, discharge, and continuing care handled?
How naloxone works
Naloxone is an opioid antagonist that can temporarily reverse the breathing suppression caused by heroin, fentanyl and prescription opioids. It acts quickly and has no intoxicating effect. It will not treat cocaine toxicity, alcohol poisoning or benzodiazepine overdose, but it should still be given when opioid exposure is possible because mixed-drug overdoses are common.
Naloxone can be administered as a nasal spray or injection, depending on the product and local availability. Anyone likely to witness an overdose can learn to use it. The package instructions and local training should be followed because devices differ.
Recognising an opioid overdose
Do not wait for complete certainty. Warning signs include inability to wake, slow or shallow breathing, pauses in breathing, gurgling or unusual snoring, blue or grey lips, limpness and very small pupils. Someone who is merely asleep should respond to voice or firm stimulation; a person who does not respond may be overdosing.
Fentanyl can cause rapid respiratory depression. Cocaine, methamphetamine and counterfeit pills may also contain fentanyl, so an overdose can occur in someone who did not intend to take an opioid.
Emergency response step by step
Call local emergency services and report an unresponsive person with possible opioid overdose.
Give naloxone according to the product instructions.
Provide rescue breathing or cardiopulmonary resuscitation according to your training and dispatcher guidance.
Give another naloxone dose if the person does not respond within the recommended interval and another dose is available.
Stay with the person, monitor breathing and place them in a safer recovery position when appropriate.
Do not put the person in a cold shower, make them walk, inject stimulants or leave them alone. These actions delay effective care.
Why more than one dose may be needed
Potent opioids such as fentanyl can outlast or exceed the effect of one naloxone dose. Delivery may also be delayed if the nose is obstructed or the device is used incorrectly. Continue ventilation support and give repeat doses as directed while waiting for emergency help.
A response to naloxone supports the possibility of opioid overdose, but lack of response does not prove that opioids are absent. Brain injury, cardiac arrest, another drug or a medical condition may also be present.
Naloxone can wear off
Naloxone often has a shorter duration than the opioid. A person who wakes can become sedated again after the naloxone effect declines. This is why emergency assessment and continued observation are necessary even when the person says they feel well or wants to leave.
Encourage the person to remain with emergency staff. Do not allow driving, further opioid use or use of alcohol and sedatives after reversal.
Withdrawal after naloxone
In a person who is physically dependent, naloxone can precipitate sudden withdrawal with agitation, sweating, vomiting, diarrhoea, aches and intense craving. These symptoms can be distressing, but breathing takes priority. Do not delay naloxone out of fear of withdrawal.
Keep the environment calm and let clinicians manage symptoms. The person may try to use opioids again to stop withdrawal, creating another overdose risk while naloxone is still active.
Naloxone in mixed-drug overdose
Alcohol, benzodiazepines, pregabalin and other sedatives can contribute to unresponsiveness and slow breathing. Naloxone reverses only the opioid component. The person may remain sedated and still needs airway support and emergency care.
Stimulant-opioid mixtures can produce an unusual sequence of agitation, collapse and respiratory depression. Treat the breathing emergency and disclose every known substance to clinicians.
Who should have naloxone
Naloxone is relevant for anyone using heroin, fentanyl, non-pharmacy pills or prescription opioids with elevated risk. It is also important after detoxification or abstinence, for people taking opioids with sedatives, and for family or peers who may be present. Because a person cannot administer naloxone to themselves while unconscious, others need to know where it is kept.
Store it where it can be reached quickly, check expiry dates and replace used doses. Extreme temperatures can damage some products, so follow storage instructions.
Planning with family and peers
Practise recognising overdose and using the actual device. Agree that emergency services will be called even if naloxone works. Fear of blame or legal consequences should not delay a life-saving response.
Families can place kits in more than one location and include them in travel plans. Children should not play with the device, but responsible adolescents and adults can be trained when appropriate.
After an overdose
An overdose is a strong indicator that current treatment and safety measures are insufficient. Before discharge, the person should be offered medication for opioid use disorder, replacement naloxone and rapid follow-up. Review tolerance, supply, sedatives, housing and whether use occurred alone.
Buprenorphine or methadone can reduce exposure to unpredictable illicit opioids. The guide to medications for opioid use disorder explains these treatments.
Naloxone is not a substitute for treatment
Naloxone saves lives and creates another opportunity for care. It does not remove opioid dependence, craving or the conditions that led to use. People may experience several overdoses if the underlying disorder and supply risk remain unchanged.
Overdose education should therefore be paired with accessible treatment, housing and mental-health support. Punishing or discharging someone after overdose can increase the chance of a future fatal event.
Naloxone in residential and luxury rehab
Every service treating opioid use should have naloxone, trained staff and a clear emergency pathway. A private or luxury rehab should explain who responds overnight, how quickly emergency services can reach the residence and whether naloxone is supplied at discharge.
Remote accommodation without reliable emergency access can create additional risk. Verify actual clinical practice, not only written claims.
Common misconceptions
Giving naloxone does not encourage opioid use. It does not produce euphoria and has no effect in a person without opioids in their system. It is not possible to judge who “deserves” it during an emergency; the priority is restoring breathing.
Learning overdose response is comparable to learning first aid. It complements prevention and treatment rather than replacing them.
Frequently asked questions
Can this condition be treated?
Yes. Treatment should be matched to the substance or behaviour, severity, withdrawal and overdose risk, physical and mental health, previous response, goals, and available support. More than one episode of care may be needed.
Does withdrawal mean someone has an addiction?
Not necessarily. Withdrawal can indicate physical dependence, including during appropriate prescribed treatment. Addiction additionally involves impaired control, prioritisation, and continued use despite harm. A clinician can distinguish these patterns.
What is the safest first step?
Arrange a confidential assessment with a qualified addiction or medical service. Use emergency services immediately for overdose, seizure, breathing difficulty, severe confusion, dangerous psychosis, or immediate suicide risk.
Sources and clinical guidance
Sources are selected for clinical authority and public accessibility. Publication does not imply endorsement of any treatment provider.
Yes. Treatment should be matched to the substance or behaviour, severity, withdrawal and overdose risk, physical and mental health, previous response, goals, and available support.
Does withdrawal always mean someone has an addiction?
No. Withdrawal can indicate physical dependence, including during appropriate prescribed treatment. Addiction additionally involves impaired control, prioritisation, and continued use despite harm.
What is the safest first step?
Arrange a confidential assessment with a qualified addiction or medical service. Use emergency services immediately for overdose, seizure, breathing difficulty, severe confusion, dangerous psychosis, or immediate suicide risk.
Prepared by the AddictionInfo Editorial Team and last evidence-checked on September 4, 2026. We distinguish education from medical advice, link material claims to primary or authoritative sources, and correct substantive errors transparently. Read our editorial standards.
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