Published: 08/4/2026 | Author: Nikki Wisher

For years, the working assumption in overdose prevention was that injecting carried the highest risk and that moving away from it lowered that risk. A new analysis of people affected by heroin addiction in Baltimore complicates the picture. It found no evidence that any one route of use was riskier than another. In this case, higher overdose odds correlated with using several routes during the same period.

The study matters because the way folks in the United States use opioids has changed sharply since 2020. Even though states like Maryland feature a wide range of addiction treatment programs, from inpatient care in modern facilities to local Narcotics Anonymous chapters, the shifting drug scene continues to take its toll on residents and their families.

The Opioid Crisis in Baltimore

Drug overdoses have caused more than one million deaths in the United States since 1999, according to the Centers for Disease Control and Prevention. Despite efforts and funding to lower overdose numbers, the rates remain near historic highs.

The mix has shifted underneath those totals. Multiple studies documented a move away from injecting and toward smoking and nasal inhalation starting during the COVID-19 pandemic. By 2022, CDC data showed smoking-related overdose deaths had passed injection-related overdose deaths.

The Baltimore Study’s Findings

Researchers used the ALIVE cohort, a community-recruited study of adults in Baltimore who have a history of injecting drugs. Participants attend visits twice a year and report their drug use over the previous six months.

The heroin analysis covered 1,121 participants across 4,396 study visits. Of those visits, nearly 890% were from adults aged 40 to 79, 33% by women, and 77% by Black participants. Past-six-month overdose was reported at 11.6% of visits.

Injection alone was the most common pattern at 34% of visits, followed by injection with nasal inhalation at 29% and nasal inhalation alone at 28%. All three routes together accounted for 4%.

Using all three routes associated with higher overdose odds than injecting alone, with an adjusted odds ratio of 2.37. Compared with nasal inhalation, the adjusted odds ratio was 2.87. Using both injection and nasal inhalation associated with higher odds than just nasal inhalation, at 1.78. The authors reported similar patterns for cocaine.

The Design Matters Regardless of Location

Earlier research on this question was largely cross-sectional. This means it compared different people at a single point in time. That approach cannot separate the effect of a route from everything else that differs between people, including which drugs they use, how often, and at what potency.

This analysis instead looked at within-person change. It asked whether the same participant had different overdose odds during periods when they used drugs differently. This was the first study to examine the relationship this way in a longitudinal, community-recruited sample.

The finding doesn’t offer a direct proof of cause. It’s also based on one cohort in one city whose participants all have a history of injecting, even as the overdose rates in Maryland have fallen from its peak. It shouldn’t be read as guidance for any individual.

Fentanyl’s Role in the Shift

The authors situate their work against a changing drug supply. Fentanyl became more common in non-injection formulations before and during the pandemic. Xylazine emerged as a contaminant. Harm reduction services, routine health care and treatment access were all disrupted.

Fentanyl’s presence means the contents and strength of a given supply are frequently unknown to the person using it. That unpredictability partly explains why the authors treat unfamiliar or shifting use practices as worth studying.

Opioids and How to Handle Overdose

Opioid classifications include heroin, fentanyl and prescription meds. They act on receptors in the brain and spinal cord that regulate pain, and at high enough doses they slow or stop breathing, which is what makes an overdose fatal.

Naloxone, sold under brand names including Narcan, reverses an opioid overdose by displacing opioids from those receptors. It is available over the counter and works within minutes.

Harm reduction programs supplying sterile equipment for drug administration may help people who use drugs reduce overdose risk. That is their recommendation based on these findings, and approaches to equipment distribution vary by state and locality.

Beyond equipment, medication for opioid use disorder remains the most established treatment for heroin addiction. Buprenorphine and methadone reduce withdrawal and cravings by acting on the same receptors, and naltrexone blocks opioid effects after withdrawal is complete. These medications are typically paired with counseling.

Peer support runs alongside treatment rather than replacing it. Narcotics Anonymous meetings give people in recovery from heroin addiction and other opioid use disorders regular contact with others working through the same thing, and meetings are free to attend.

NA a First Defense Against Heroin Addiction

If you or someone close to you is dealing with heroin addiction or another opioid use disorder, several steps are available now.

• Get naloxone and keep it accessible. Pharmacies stock it over the counter, and many local harm reduction programs distribute it at no cost.
• Ask about fentanyl test strips, where they’re legal and available.
• Contact an opioid treatment program or a buprenorphine prescriber to discuss medication options.

Our online directory lists NA meetings by state and city, with filters for meeting type and virtual options. You can find something nearby without waiting for an appointment. Feel free to browse our listings or call 800-934-1582(Sponsored) to speak with an expert.