naloxone hydrochloride dihydrate at a glance
Medicine class
Opioid antagonist and emergency antidote
Main role
Reverses opioid-related respiratory and central nervous system depression
Available routes
Selected products include a single-use nasal spray and injectable solutions for professional administration
Emergency action
Call 999, support breathing as trained and stay with the person even if they wake up
What is naloxone hydrochloride dihydrate used for?
Selected products are licensed for opioid-related emergencies and reversal.
Emergency treatment of known or suspected opioid overdose with respiratory or central nervous system depression; the selected nasal spray is licensed for adults and adolescents aged 14 years and over.
Reversal of respiratory and central nervous system depression caused by natural or synthetic opioids, including after medical opioid use.
Supporting diagnosis of suspected acute opioid overdose or intoxication using injectable naloxone.
Reversal of respiratory and central nervous system depression in a newborn following opioid analgesia given to the mother during childbirth, using selected injectable products.
How does naloxone hydrochloride dihydrate work?
Naloxone competes with opioids at opioid receptors and displaces opioid agonists and partial agonists. It can restore breathing and consciousness, but its effect may wear off before the opioid does. It does not reverse unconsciousness or respiratory depression caused solely by non-opioid substances.
naloxone hydrochloride dihydrate preparations and strengths
Nasal preparation
Route: Nasal
Strengths: 1.8 mg
Injection
Route: Parenteral
Strengths: 400 micrograms/1 mL, 400 micrograms/mL, 0.4 mg/mL
How to take naloxone hydrochloride dihydrate
Naloxone is used in an emergency rather than taken routinely. Call 999 before or immediately after administration and follow product-specific training.
For the nasal product, do not prime or test the single-use device. Insert the nozzle gently into a nostril and press the plunger firmly until it clicks.
After nasal administration, place a breathing person in the recovery position, monitor breathing and responsiveness, and stay until emergency services arrive.
Injectable products are administered by appropriately trained people or healthcare professionals by a route suitable for the product and clinical setting.
naloxone hydrochloride dihydrate side effects
Common or expected effects
- Feeling sick or being sick
- Dizziness or headache
- Fast heartbeat
- Raised or lowered blood pressure
- Return of pain when opioid analgesia is reversed
Get urgent medical advice
- Severe allergic reaction with facial or throat swelling, breathing difficulty or collapse
- Dangerous heart-rhythm disturbance, severe chest symptoms or cardiac arrest
- Fluid in the lungs or worsening breathing difficulty
- Severe acute opioid withdrawal, including marked agitation, vomiting, sweating, rapid heartbeat, raised blood pressure or seizures
naloxone hydrochloride dihydrate in pregnancy
Human pregnancy data are limited. Naloxone may be used when emergency opioid reversal is required; treatment should not be delayed solely because of pregnancy. It can precipitate withdrawal in an opioid-dependent woman or newborn, and fetal monitoring is advised after nasal naloxone treatment.
naloxone hydrochloride dihydrate while breastfeeding
Advice differs by formulation. Selected nasal spray information says breastfeeding need not be interrupted but recommends monitoring the infant for sedation or irritability. Selected injectable product information advises temporary avoidance after treatment. Specialist advice should consider the formulation, the mother's condition and opioid exposure.
naloxone hydrochloride dihydrate interactions
Most clinically important effects arise from naloxone opposing opioids or from mixed-drug poisoning.
Opioids used for pain relief
Naloxone can reduce or remove analgesia and may cause pain or acute withdrawal in someone who is opioid-dependent.
Buprenorphine
Reversal of buprenorphine-related respiratory depression may be incomplete, so ventilatory support may still be required.
Common questions about naloxone hydrochloride dihydrate
Answers are fully visible for fast scanning and source review.
Does naloxone hydrochloride dihydrate work for every type of overdose?
No. It reverses opioid effects but does not directly reverse alcohol, benzodiazepines, stimulants or other non-opioid substances. Emergency assessment is still required because mixed poisoning is common.
Why must 999 be called after giving naloxone hydrochloride dihydrate?
Naloxone is temporary and the opioid may remain active for longer, allowing breathing problems or unconsciousness to return. Ambulance care and continued observation are essential.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.