Naloxone: uses, side effects & brands

Written & medically reviewed by Dr. Sanjay Anbu, MBBS · Last reviewed 5 November 2026

Naloxone rapidly reverses an opioid overdose. It belongs to the Emergency & critical-care medicine group. These are used in medical emergencies, usually by trained staff.

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Drug type — dosing is set by your doctor

Measure	Range
Drug class	Emergency & critical-care medicine
Type	Prescription
Dose	Individual — ask your doctor or pharmacist

What it is used for

Emergency reversal of an opioid overdose
Reversing breathing problems caused by opioids after surgery
Suspected opioid poisoning in someone who is unresponsive

Common brand names

India: Nalox, Narcotan
Worldwide: Narcan

Common side effects

Sudden opioid withdrawal: sweating, shaking, vomiting, agitation
Fast heartbeat or raised blood pressure
Return of pain that the opioid was controlling

Before taking it — precautions

Its effect can wear off before the opioid's does, so the person must still get emergency care
People dependent on opioids may go into sudden withdrawal
Tell the doctor about heart disease

When to see a doctor urgently

Breathing slows or the person becomes drowsy again after waking (urgent)
Chest pain, very fast heartbeat or fits (urgent)
Severe breathlessness or coughing frothy fluid (urgent)

Not a prescription — no dose shown. The right dose of naloxone depends on age, weight, kidney/liver function and the condition, so MedDroid does not show a dose here. Always get your dose from a doctor or pharmacist and the leaflet inside the pack. General educational information only.

Frequently asked questions

Is naloxone safe to give if I am not sure it is an opioid overdose?

It has little effect in someone who has not taken opioids, so it is generally safe to give in a suspected overdose. Always call emergency services as well.

Why must someone stay with the person after naloxone?

Naloxone can wear off sooner than the opioid, and breathing may slow again. Stay with them until medical help arrives.

Does naloxone work on alcohol or sleeping-pill overdoses?

No. It only reverses opioids such as morphine, heroin, tramadol or fentanyl.

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Sources & further reading

Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.