What is Nalmefene Nasal Spray: Uses, Dosage, Side Effects and More

Nalmefene nasal spray is a life-saving medication that can reverse opioid overdoses within minutes. It blocks opioid receptors in your brain, quickly counteracting the dangerous effects of too much heroin, fentanyl, prescription painkillers, or other opioids.

This medication comes as a ready-to-use nasal spray that anyone can learn to administer during an emergency. Think of it as an emergency reset button for someone whose breathing has slowed or stopped due to an opioid overdose.

What is Nalmefene Used For?

Nalmefene nasal spray treats suspected opioid overdoses when someone has taken too much of these substances. You might need it if someone around you has used heroin, fentanyl, oxycodone, morphine, or other opioid medications and shows signs of overdose.

The most concerning signs include very slow or absent breathing, blue lips or fingernails, unconsciousness, and inability to wake the person even with loud noises or pain. These symptoms mean the person's brain isn't getting enough oxygen, which can become fatal within minutes.

Emergency responders, family members, and friends of people who use opioids often carry this medication. It's designed for situations where every second counts and professional medical help might not arrive quickly enough.

How Does Nalmefene Work?

Nalmefene is a powerful opioid antagonist that works by blocking opioid receptors in your brain. When opioids flood these receptors during an overdose, they slow down critical functions like breathing and heart rate.

This medication acts like a key that fits into the same locks as opioids but doesn't turn them. Instead, it prevents opioids from accessing these receptors, effectively reversing their dangerous effects. The medication works within 2 to 5 minutes after administration.

Nalmefene has a longer duration of action compared to naloxone, typically lasting 4 to 6 hours. This extended protection is especially important with long-acting opioids like methadone or sustained-release formulations that could cause symptoms to return.

How Should I Use Nalmefene Nasal Spray?

Using nalmefene nasal spray requires quick but careful action during an emergency. First, call 911 immediately before administering the medication, as professional medical care is always necessary after an overdose.

Remove the device from its packaging and insert the tip firmly into one nostril. Press the plunger firmly and quickly to deliver the entire dose. The person doesn't need to inhale or be conscious for the medication to work.

Here's what to do step by step when you suspect an overdose:

1. Call 911 or emergency services immediately
2. Check if the person is responsive by shouting their name or rubbing their chest
3. Remove nalmefene from packaging and insert into nostril
4. Press plunger firmly to deliver full dose
5. Begin rescue breathing or CPR if trained
6. Stay with the person until emergency help arrives

If the person doesn't respond within 2 to 3 minutes, you may need to give a second dose in the other nostril. Continue rescue efforts and wait for professional medical help to arrive.

How Long Should I Keep Nalmefene Available?

Nalmefene nasal spray should be kept readily available as long as there's a risk of opioid overdose in your environment. The medication has an expiration date printed on the package, typically lasting 2 to 3 years when stored properly.

Store the device at room temperature, away from heat and direct sunlight. Don't keep it in extremely hot places like car glove compartments or extremely cold areas like freezers, as temperature extremes can affect its effectiveness.

Replace expired devices promptly and consider having multiple units available in different locations if you're caring for someone at high risk. Many people keep one at home, one in their car, and one at work or other frequently visited places.

What Are the Side Effects of Nalmefene?

The person receiving nalmefene may experience withdrawal symptoms as the medication blocks opioid effects. These symptoms are uncomfortable but not life-threatening, and they indicate the medication is working properly.

Common withdrawal symptoms that may appear quickly include:

• Nausea and vomiting
• Sweating and chills
• Rapid heartbeat
• Anxiety or agitation
• Muscle aches and pains
• Runny nose and tearing

These symptoms occur because the body has become dependent on opioids, and suddenly blocking their effects creates a rebound reaction. While distressing, these symptoms confirm that the medication is successfully counteracting the overdose.

The person may also experience confusion, dizziness, or headache as their brain adjusts to the medication. Some people become combative or agitated as they regain consciousness, which is why it's important to stay calm and keep them safe.

Rarely, some people may experience more severe reactions like seizures, irregular heartbeat, or difficulty breathing. These serious side effects require immediate medical attention, which is why calling 911 before giving the medication is so crucial.

Who Should Not Use Nalmefene?

Nalmefene is generally safe for emergency use, but there are some important considerations. People with known allergies to nalmefene or similar medications should avoid it, though in a life-threatening overdose, the benefits typically outweigh the risks.

Pregnant women who use opioids regularly may experience complications if given nalmefene, as it can trigger withdrawal symptoms that could affect the baby. However, saving the mother's life takes priority, and medical professionals can manage any complications that arise.

People with severe heart disease may be more sensitive to the rapid changes that occur when opioids are suddenly blocked. Their heart rate and blood pressure may fluctuate more dramatically, requiring careful monitoring by medical professionals.

Those taking certain medications for depression or other mental health conditions may experience intensified withdrawal symptoms. This doesn't mean they shouldn't receive nalmefene in an emergency, but they may need additional medical support during recovery.

Nalmefene Brand Names

Nalmefene nasal spray is available under the brand name Opvee in the United States. This is the primary commercial formulation designed for emergency overdose reversal by non-medical personnel.

The medication may also be available through different manufacturers or under generic names in some regions. However, the specific nasal spray formulation for overdose reversal is most commonly known as Opvee.

Some hospitals and emergency services may use injectable forms of nalmefene, but these require medical training to administer safely. The nasal spray version is specifically designed for use by family members, friends, and first responders without extensive medical training.

Alternatives to Nalmefene

Naloxone nasal spray (Narcan) is the most common alternative to nalmefene for overdose reversal. Both medications work similarly by blocking opioid receptors, but they have some important differences in duration and strength.

Naloxone typically works for 30 to 90 minutes, which is shorter than nalmefene's 4 to 6 hours of protection. This means people given naloxone may need repeat doses or could experience return of overdose symptoms as the medication wears off.

Injectable naloxone is available for medical professionals and trained individuals, offering very rapid onset but requiring needles and proper injection technique. Auto-injector devices like Evzio provide pre-measured doses with voice instructions for emergency use.

The choice between these medications often depends on availability, the specific opioids involved, and local emergency protocols. Many communities focus on naloxone distribution due to its widespread availability and lower cost.

Is Nalmefene Better Than Naloxone?

Nalmefene offers longer-lasting protection against opioid overdose compared to naloxone, which can be crucial with powerful or long-acting opioids. Its 4 to 6-hour duration provides more safety margin than naloxone's 30 to 90 minutes.

This extended protection is particularly valuable with fentanyl and other potent synthetic opioids that can cause overdose symptoms to return quickly. Nalmefene's longer action may reduce the need for multiple doses or the risk of re-overdose.

However, naloxone has been available longer and is more widely distributed through community programs. Many first responders and family members are already trained in its use, and it's often available at lower cost or even free.

Both medications are highly effective at reversing overdoses when used properly. The "better" choice depends on factors like the specific opioids involved, availability in your area, and your comfort level with the device.