This investigation on the fentanyl crisis in Puerto Rico was made possible thanks to a grant from the Fund for Investigative Journalism.

Leslie Marie Pérez Hernández never imagined that a single pill would end her life at just 29 years old, leaving her family devastated.

“She didn’t know the pill had fentanyl in it,” said her mother, Daisy Hernández Acevedo. “She was happy, she loved the beach, she liked to help others, she loved animals, she had a noble heart, she didn’t want to die.”

Leslie thought she was taking Xanax. 

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“They poisoned her,” said her mother, who added that it’s extremely difficult to identify when pills have been laced with fentanyl on the black market. A dangerous and powerful synthetic opioid, fentanyl is up to 50 times more powerful than heroin and 100 times stronger than morphine.

Her daughter died July 1, 2020, a date now deeply etched in Daisy’s mind. Ever since, she counts the years, months and days without her beloved Leslie.

“It’s been horrible for me,” she said. 

Daisy Hernández Acevedo and her daughter Leslie Marie Pérez Hernández in better times. (Photo provided by the familiy)

Daisy isn’t alone. Over the past four years, nearly 2,000 people in Puerto Rico have faced the same fate as her daughter, in a “silent epidemic” of overdose deaths from fentanyl. The majority of victims are young adults, with 16- and 17-year-old minors also among the dead.

It’s a trend linked with a rise in the sale of fentanyl-laced pills on the black market. Though the problem dates back to 2013, when sales of the drug peaked in the United States, it wasn’t until 2020 that Puerto Rico’s Institute of Forensic Sciences (Instituto de Ciencias Forenses, ICF) began to consistently test for fentanyl in all cases of suspected overdose or violent death, leading to more reliable statistics, explained ICF executive director María Conte Miller. 

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* ICF deaths estimate for 2023 because toxicologic exams for the period are not finalized.

Leslie tried her first Xanax pill at age 19 to calm anxiety symptoms. That was 2010. Eight years later, in 2018, Daisy noticed one day that her daughter seemed ill, and took her to the hospital. That’s when  Leslie confessed she took Xanax—not prescribed by a doctor—regularly to calm anxiety.

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Daisy figured it was just a phase and that, with the right support, Leslie would stop taking them. But that didn’t happen. 

“Sometimes these substances or pills tend to change the functioning of the brain and it becomes more of a disease, so it’s really hard to convince someone to stop,” she said.

Since 2020, deaths from fentanyl, either alone or in combination with other drugs, have increased dramatically in Puerto Rico. Fentanyl is now the leading cause of overdose on the island. According to ICF data, over 60% of overdose deaths during this period included the presence of fentanyl in toxicological tests; 90% of these deaths affected men. Men between 34 and 43 years old are the most affected, accounting for almost 17% of deaths.

There were 374 deaths due to fentanyl overdose recorded in 2023—a figure that’s incomplete because a number of toxicological tests are still pending, explained Conte Miller. 

Toxicology tests can take up to three months, the pathologist said. She projects that fentanyl-related deaths in 2023 will reach those recorded in 2022, when 636 people died from the drug. 

The ICF was lacking reagents for fentanyl tests

Despite the incidence of fentanyl-related deaths across the United States since the early 2000s, broad and structured testing to detect fentanyl in Puerto Rico didn’t begin until 2020. That’s because of internal problems at the ICF, Conte Miller admitted. 

“The Institute was facing a series of situations; we didn’t have reagents to carry out tests, and the laboratory wasn’t working well,” said the forensic pathologist. “When things began to work better and we were able to get reagents, we were able to start testing (consistently).” 

By protocol, all people who are suspected of having died due to an overdose or a violent death undergo toxicological testing. Of those tested, some are found to have died for a reason besides drugs, even when drugs are present in their system. For instance, someone who died in a traffic accident may also test positive for drugs.

In the early 2000s, it was common to detect opioids such as morphine and heroin in tests, but that’s no longer the case, she said. Now, fentanyl or a combination of fentanyl and cocaine are the most common drugs detected in overdose cases. Toxicologists are also seeing a higher incidence of xylazine, a veterinary tranquilizer, mixed with fentanyl. 

Pharmaceutical fentanyl is prescribed by doctors to treat severe pain. The problems stem from fentanyl sold illegally on the streets, she said, which is mixed with other substances unbeknownst to a user, she said.

“The real problem is at the drug selling point,” said the ICF director, adding that overdose deaths in Puerto Rico have surpassed homicides.

Arnaldo Cruz Igartua, psychiatrist specialist in addiction and director of the Multidisciplinary Fellowship in Addiction Medicine at the Central University of the Caribbean, explained that fentanyl is 50 to 100 times more powerful than morphine and 25 to 50 times more powerful than heroin, and is injected or swallowed. 

“Fentanyl is what’s sold underground now” 

According to Andrés Calvo, an internist and specialist in addiction medicine, the increase in deaths from fentanyl versus those previously caused by heroin or oxycontin is because “Fentanyl is what’s sold underground now.”

Finding pure heroin or heroin without fentanyl is nearly impossible now, he said. Heroin is also more expensive. For the most part, heroin users know they’re going to get something that contains fentanyl, so it’s not a surprise. 

At the same time, there’s been an increase in cases of accidental overdose, where a person consumes a substance without knowing it contains fentanyl, as explained by Conte Miller. This happens mostly with pills.

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Fentanyl deaths are also prevalent in prisons. In 2023, 35% of the 77 deaths recorded in Puerto Rican prisons, or 27 deaths, were from overdoses. Of those, all but one were from fentanyl, according to ICF data.

Most deaths in prisons are due to illnesses, including those caused by substance abuse and cardiovascular disease, followed by accidents, a category which includes overdoses, Conte Miller explained.

But the magnitude of the fentanyl problem in Puerto Rico goes far beyond fentanyl deaths, according to information collected by the Mental Health and Addiction Services Administration (ASSMCA) on overdoses not resulting in death. 

Carmen Bonet Vázquez, administrator of the agency, said in an interview with Es Mental that, although the data reflects an increase in overdoses, a higher percentage of overdoses have also been reversed, mainly with the use of naloxone, according to data recorded in an agency monitoring system. Naloxone is a medication designed to rapidly reverse opioid overdose. 

The data collected by ASSMCA comes from questionnaires filled out by people who received and used naloxone. The agency also receives information from nonprofit organizations.

According to these reports, from 2019 to 2023, there were 4,281 recorded overdoses. Of those, 4,121 were non-fatal due to the use of naloxone. 

The route of fentanyl trafficking to Puerto Rico

José Velázquez, DEA public relations specialist for Puerto Rico and the Caribbean, said fentanyl is arriving to the island mainly via mail and by smugglers.

It originates from Mexico; Mexican cartels buy fentanyl-related substances in China, and then manufacture it into fentanyl.

“Once it’s manufactured in these clandestine laboratories, it’s sent first in the continental United States,” he said. “Then it reaches Puerto Rico and other places.” 

Fentanyl arrives mainly in pills, which are identical to pills manufactured by pharmaceutical companies, he said. He agreed with Conte that the problem stems from drug contamination, especially fentanyl-laced pills, and not from fentanyl used for medical purposes. 

A mere two milligrams of fentanyl is potentially fatal. That’s equivalent to six grains of salt, he said. “That fits on the tip of a pencil.” 

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“We see 5 milligram pills. The average at the [DEA] laboratory in Miami is 8 milligrams per pill,” he said.

There are no controls in underground labs. Manufacturers “don’t want to kill their users but they don’t have the capacity to make that type of drug without it being fatal,” he said.

In Puerto Rico, when people can’t get their medications at the pharmacy, they often look for them on the streets. The fentanyl they may find there is being mixed mainly with cocaine, xylazine and pills.

The DEA has ramped up seizures of the drug in Puerto Rico. In 2023 the agency confiscated 17 kilos of fentanyl (used for mixing), up from 14 kilos in 2022. They’ve seen a reduction in pharmaceutical fentanyl: in 2023 they confiscated about 1 kilo, down from 1.29 in 2022.

In 2023, the DEA confiscated more than 30,000 illegal pills, of which 27,272 contained fentanyl. Seventy percent—7 of every 10 pills seized—had a potentially fatal dose of fentanyl. 


These figures are only from DEA seizures; other agencies—such as the police—also have their own numbers.  

Government efforts to counter the epidemic

The government is implementing efforts to prevent overdose deaths, such as through the establishment of a pilot system to provide real-time alerts when a person in a hospital or emergency room is showing signs of overdose, said Eduardo Zavala Mendoza, principal investigative officer of the Puerto Rico Department of Health (DSPR) opioid program.

The alerts are received by counselors, psychologists or social workers, known as “navigators,” he explained. 

“This type of case management isn’t just to ensure that the person is treated appropriately in the emergency room, but also to do everything possible to link that person with treatment,” he said. “We know that the probability of a fatal overdose increases considerably if the person isn’t referred to treatment, so we’re trying to reduce deaths from any overdose.”

In October, Puerto Rico’s Secretary of Health Carlos Mellado signed an administrative order that mandated all emergency rooms and urgent care facilities to adopt a protocol for the use of buprenorphine and to link patients to treatment. Buprenorphine is a drug used to treat opioid dependence. 

But it’s still being rolled out, and not currently in place in all hospitals in Puerto Rico. According to Zavala Mendoza, 60 emergency and urgent care rooms now have a protocol approved by the DSPR and 21 are in process of adopting one.

In fact, the Secretary of Health’s order came after a study revealed that only 48% of emergency rooms had some type of “guideline” in place for the management of overdoses.

The Department of Health is also working on a collaboration with the ICF to allocate almost $2 million to strengthen capabilities for the analysis of and differentiation between licit and illicit fentanyl overdose.

Like ASSMCA, the department regularly distributes fentanyl test strips, used to determine if a substance has fentanyl, as well as Narcan, used to treat narcotic overdose in an emergency situation.

Zavala Mendoza said that establishing an integrated response from the government, nonprofit organizations, the community and other sectors is among the greatest challenges. 

“Another challenge is gaining trust—that what we are doing is going to have an impact,” he said. “And continuity, especially due to continual changes in the government.”  

He also said that stigma is a barrier, among both professionals who work with drug users and the general population. “Stigma kills and it’s a problem in Puerto Rico,” he said, adding that not all professionals exhibit stigmatizing behavior.

There is much to improve, said psychiatrist Cruz Igartua about government efforts to address the opioid situation on the island. “Detox programs that don’t provide referrals for buprenorphine or methadone result in a revolving door effect in hospitals where the same patients enter and leave several times in a year,” he said. 

He added, “There’s confusion between what counts as therapy and what counts as treatment consisting of multiple complementary therapies, which vary depending on the needs of each specific patient and their family.”

Often a patient leaves with lower tolerance to opioids and a greater risk of losing their life in an overdose: after detox, there’s a more than 80% probability of repeated overdose in the first three months in patients with severe addiction to any substance, including opioids, he said. “That’s why it’s essential to have long-term treatment managed by interdisciplinary teams specialized in addiction.” 

Calvo, the addiction specialist, believes the fentanyl crisis in Puerto Rico requires a stronger treatment response. “Addiction risk is higher, the risk of long-term cognitive changes is higher, and the risk of death is higher,” he said. “Unfortunately that’s the reality we’re living and I don’t think it will change.”

He added that treatment should consist of both biopsychosocial and spiritual components, with support throughout the process.

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Leslie’s mother said she will continue to speak out about the problem, including at schools and DEA conferences, for as long as young adults keep dying from fentanyl in Puerto Rico. 

“I’m doing my part so that people know the dangers of fentanyl are real, and so they don’t take any medication that isn’t prescribed,” she said. “It can happen to anyone.” 

She added: “I wish Leslie had the opportunity to understand how great the risk was, but she didn’t know what she was taking.”