Vaccine Could Prevent Fentanyl from Entering the Brain and Prevent Relapses and Overdoses

Scientists have developed a vaccine that produces antibodies that bind to the potent opioid fentanyl and block its effects, which could help people overcome opioid addiction and prevent overdoses.

Antibodies neutralize the fentanyl molecule

The vaccine, which has been tested in rats, was developed by a research team led by the University of Houston. Like other vaccines, it stimulates the immune system to produce antibodies. These antibodies bind to the fentanyl molecule and effectively neutralize it. It can’t enter the brain, eliminating the drug’s high, and is instead excreted from the body through the kidneys.

Preventing relapse

The vaccine could be administered to people trying to recover from opioid use disorder (OUD) to prevent relapse. While OUD is treatable, 80% of people will relapse at least once.

After being vaccinated, “the individual will not feel the euphoric effects [of fentanyl] and can ‘get back on the wagon’ to sobriety” after a relapse, said the study’s lead author Colin Haile, a research associate professor of psychology at the University of Houston.[1]

Doctors have already tried to use medicine to block opioids’ euphoric effects. The opioid antagonist naltrexone blocks the activation of opioid receptors and takes away the drugs’ high. But compliance with daily naltrexone is low. The FDA has approved an injectable, long-acting form of naltrexone which can neutralize the effects of opioids for weeks, but the vaccine would protect fentanyl for much longer.[2]

Preventing overdose

The fentanyl vaccine could also prevent overdoses and deaths, both among people who abuse it and those taking drugs like cocaine, methamphetamine, and even counterfeit prescription pills such as Xanax that have been cut or contaminated with the opioid. 

Fentanyl is higher potent: 50 times stronger than heroin and 100 stronger than morphine. As little as 2 milligrams, the size of two grains of rice, can be fatal. Around 71,000 overdose deaths in 2021 involved the drug.[3]

The vaccine could be administrated to people who might be purposefully or accidentally exposed to fentanyl to prevent deaths.

“Fentanyl use and overdose is a particular treatment challenge that is not adequately addressed with current medications because of its pharmacodynamics and managing acute overdose with the short-acting [opioid antagonist] naloxone is not appropriately effective as multiple doses of naloxone are often needed to reverse fentanyl’s fatal effects,” said Therese Kosten, professor of psychology and senior author on the study.


However, the vaccine only produces antibodies that are specific to fentanyl and is powerless against other opioids such as morphine and heroin. In some ways, that’s a bonus. Someone who received the vaccine could still be effectively treated with morphine for acute pain relief and during end-of-life care. 

However, they could still relapse and overdose on other opioids after receiving the vaccine.

Additionally, the vaccine hasn’t yet been tested in humans. But the immunization didn’t cause any adverse effects and clinical trials with humans are intended to start soon.

“We believe these findings could have a significant impact on a very serious problem plaguing society for years—opioid misuse,” said Haile.

Kosten agreed. It’s a potential “game changer,” she said.