Opioid Overdose: Recognition, Naloxone and the Student Nurse Response

An opioid overdose is a medical emergency. For student nurses, recognising the pattern early matters because the immediate threat is usually not the drug itself, but what it is doing to the person's breathing.

Opioids such as morphine, oxycodone, fentanyl, heroin and methadone act on opioid receptors in the central nervous system. In overdose, this can suppress the brain's respiratory drive. Breathing becomes slower and less effective, oxygen levels fall and, without treatment, respiratory arrest and cardiac arrest can follow.

This guide explains what opioid overdose can look like, why it happens, how naloxone works and what a student nurse should do when a patient deteriorates.

Why do opioids cause respiratory depression?

Opioids primarily produce their clinically important effects through opioid receptors, particularly mu-opioid receptors. These receptors are involved in analgesia but also influence consciousness and respiratory control.

At therapeutic doses, opioids can cause sedation and a reduction in respiratory rate. With excessive opioid effect, respiratory drive can become profoundly depressed. The person may take fewer breaths, breathe very shallowly or stop breathing altogether.

This is why respiratory assessment is central when opioid toxicity is suspected. A patient who is becoming increasingly drowsy after receiving an opioid should never be assessed on consciousness alone. Look at their breathing as well.

What might an opioid overdose look like?

The classic pattern is reduced consciousness, respiratory depression and pinpoint pupils. However, real patients do not always present exactly like a textbook.

• Increasing drowsiness or inability to stay awake
• Difficulty rousing the person or complete unresponsiveness
• Slow, shallow, irregular or absent breathing
• Snoring, gurgling or choking sounds
• Very small pupils, although this is not always present
• Reduced oxygen saturation
• Cyanosis or abnormal skin colour, although colour changes can be more difficult to recognise on darker skin tones
• Bradycardia and hypotension in severe toxicity

A person who is unresponsive and not breathing normally requires immediate emergency assessment and intervention. Do not assume they are simply asleep or that sedation is an expected effect of the opioid.

Think ABCDE, not just 'overdose'

On placement, the safest approach to an acutely deteriorating patient is structured assessment. Use the ABCDE approach while calling for appropriate help.

A: Airway

Is the airway patent? Reduced consciousness increases the risk of airway obstruction. Snoring may indicate partial airway obstruction rather than normal sleep.

B: Breathing

This is particularly important in suspected opioid toxicity. Assess respiratory rate, depth and pattern, oxygen saturation and the overall effectiveness of ventilation. A falling respiratory rate in an increasingly drowsy patient is a significant warning sign.

C: Circulation

Assess pulse, blood pressure, capillary refill and other signs of circulatory compromise. Severe poisoning can be associated with hypotension and bradycardia.

D: Disability

Assess level of consciousness using an appropriate method such as AVPU or the Glasgow Coma Scale where indicated. Examine the pupils and consider blood glucose because hypoglycaemia is an important reversible cause of altered consciousness.

E: Exposure

Look for additional information that may explain the deterioration, while maintaining dignity. This might include medication patches, medicines nearby, evidence of injury or other clinical signs. Do not assume that opioid use is the only possible cause.

What should happen immediately?

Resuscitation Council UK guidance recommends calling 999 for suspected opioid poisoning in the community. If the person is unresponsive and not breathing normally, CPR should be started. Naloxone should be administered when appropriate and the person reassessed using ABCDE.

In hospital, activate the local emergency response immediately and follow local resuscitation and medicines policies. Priorities remain airway management, supporting breathing and circulation, appropriate oxygen therapy, monitoring, timely naloxone where indicated and escalation to the clinical team.

As a student nurse, do not wait until you have worked out exactly what has happened before escalating. Recognising that the patient is deteriorating and calling for help is itself an important clinical action.

What is naloxone?

Naloxone is an opioid antagonist. It competes with opioids at opioid receptors and can temporarily reverse opioid-induced respiratory depression.

In simple terms, if an opioid is suppressing the person's breathing, naloxone can displace the opioid from its receptors sufficiently to allow respiratory function to improve.

Naloxone only reverses opioid effects. It does not reverse toxicity caused solely by alcohol, benzodiazepines or other non-opioid substances. Mixed overdoses are common, so a person may remain sedated even when the opioid component has been treated.

UK legislation allows anyone to administer available naloxone for the purpose of saving a life in an emergency. Take-home naloxone may be supplied as an intranasal preparation or an injectable preparation depending on the programme and product available.

Why might more than one dose be needed?

Naloxone does not always produce an immediate or complete response after one dose. Further doses may be required according to the product instructions, clinical situation and local protocol.

Potent synthetic opioids, including fentanyl and nitazenes, may require a greater total amount of naloxone to reverse respiratory depression. This does not change the basic principle: administer the standard dose as directed, reassess the person and repeat treatment when indicated.

Public Health Scotland advises giving community naloxone doses one at a time, observing for a response and repeating doses at intervals according to the product guidance and emergency response instructions.

The patient wakes up. Is the emergency over?

No. This is one of the most important points to understand.

Naloxone may wear off before the opioid responsible for the overdose. Respiratory depression can therefore return after an apparently successful response. This is sometimes described as recurrent toxicity or re-overdose.

The person needs continued observation, repeated assessment and emergency medical care. Monitor consciousness and breathing closely and be prepared for further deterioration.

In the community, stay with the person until emergency services take over. If they are unconscious but breathing normally, position them appropriately and continue monitoring. If normal breathing is lost, begin resuscitation as directed.

Why is naloxone used differently in some hospital patients?

The aim of naloxone treatment is to restore adequate ventilation, not necessarily to make every patient completely awake immediately.

This distinction is particularly important in people receiving long-term opioids. Rapid or excessive reversal can precipitate acute opioid withdrawal and severe pain. In clinical settings, naloxone may therefore be titrated carefully by appropriately trained clinicians according to the patient's respiratory status, opioid exposure and local medicines guidance.

For a student nurse, the important lesson is not to memorise a universal naloxone dose. Recognise respiratory depression, escalate promptly, support ABCDE assessment and understand why the registered clinician may give naloxone incrementally.

Placement scenario

You are looking after a patient who returned from theatre two hours ago. They have received opioid analgesia. Earlier they were awake and talking, but they are now increasingly difficult to rouse.

You count a respiratory rate of 7 breaths per minute. Their breathing looks shallow and their oxygen saturation has fallen.

What matters first?

Do not simply document that the patient is sleepy after analgesia. Recognise the combination of reduced consciousness and respiratory depression as significant deterioration.

Call for immediate clinical help, begin an ABCDE assessment, ensure appropriate monitoring and prepare to assist the registered team with emergency management. The team will review recent medication, consider opioid toxicity alongside other causes of deterioration and administer naloxone if clinically indicated.

This is the difference between noticing a number and interpreting what that number means.

What can a student nurse do?

Your role depends on your stage of training, competence, supervision and local policy, but you can still contribute significantly.

• Recognise an abnormal respiratory rate and reduced level of consciousness.
• Escalate deterioration immediately.
• Use an ABCDE structure when assessing the patient.
• Call the emergency team or use the local emergency system when required.
• Begin basic life support within your training if the patient is unresponsive and not breathing normally.
• Bring emergency equipment and assist the registered team.
• Communicate recent opioid administration, prescribed medicines and any known substances taken.
• Continue observations and reassessment after treatment.
• Document observations, escalation and interventions accurately under appropriate supervision.

Stigma can interfere with clinical care

Opioid overdose is not limited to illicit drug use. It may occur following prescribed opioids, accidental dosing errors, recreational drug use, counterfeit medicines or exposure to unexpectedly potent synthetic opioids.

Use neutral, person-centred language. Avoid labels such as 'addict' or assumptions about why a substance was taken. Asking what was taken, when and approximately how much is clinically useful. Judging the person is not.

After the immediate emergency, some people may benefit from drug and alcohol services, take-home naloxone, harm-reduction support, mental health assessment, safeguarding input or review of prescribed medicines.

Remember

When you suspect opioid overdose, think breathing first. Reduced consciousness matters, but respiratory depression is the immediate life-threatening problem. Escalate early, assess systematically, support ventilation and understand that naloxone is a temporary reversal rather than the end of the patient's care.

References

Department of Health and Social Care (2025) Supplying take-home naloxone without a prescription. GOV.UK. Available at: https://www.gov.uk/guidance/supplying-take-home-naloxone-without-a-prescription.

Public Health Scotland (2026) Recognising and responding to an overdose: In an emergency. Available at: Public Health Scotland.

Public Health Scotland (2026) Recognising and responding to an overdose: Naloxone. Available at: Public Health Scotland.

Resuscitation Council UK (2025) Adult basic life support guidelines. Available at: Resuscitation Council UK.

Resuscitation Council UK (2025) First aid guidelines. Available at: Resuscitation Council UK.