by Caspian Whitlock - 9 Comments

Heatwaves and overdoses aren’t just coincidental-they’re connected

When the temperature climbs above 24°C (75°F), the risk of overdose doesn’t just go up-it spikes. This isn’t speculation. Data from New York City shows that during heatwaves, emergency calls for drug overdoses rise by 22%. In places like the Pacific Northwest, where summers used to be mild, overdose rates during heat events jumped 3.7 times higher than normal. Why? Because heat changes how your body processes drugs-and not in a way that keeps you safe.

How heat turns a normal dose into a deadly one

When it’s hot, your body works harder to stay cool. Your heart beats faster-up to 25 extra beats per minute at rest. If you’re using stimulants like cocaine or meth, that heart rate jumps another 30-50%. Put them together, and your cardiovascular system is under extreme stress. Your body can’t handle it. That’s when heart attacks or strokes happen, even in people who’ve used drugs before without issue.

Dehydration makes it worse. Losing just 2% of your body weight in fluids-something that happens quickly in the heat-concentrates drugs in your bloodstream by 15-20%. That means a dose you normally take could now be stronger than you realize. For opioids, heat reduces your body’s ability to compensate for slowed breathing. That tiny margin between feeling high and stopping breathing? It disappears.

Even medications for mental health can turn dangerous. About 70% of antipsychotics and 45% of antidepressants lose effectiveness or cause worse side effects in high heat. If you’re on one of these and you’re using drugs on top of it, your body has no buffer left.

People experiencing homelessness are at the highest risk

More than half a million people in the U.S. are homeless on any given night. Nearly 40% of them have a substance use disorder. When the heat hits, they don’t have air conditioning. They don’t have cool water nearby. They can’t just go inside. Shelters often turn people away if they’re actively using drugs. Some cities have even confiscated cooling supplies from outreach workers.

Urban areas are even hotter than the countryside-up to 5°C warmer because of concrete, asphalt, and lack of trees. That’s not just uncomfortable. It’s life-threatening for someone who’s already vulnerable.

What you can do: Practical harm reduction steps

If you or someone you know uses drugs, here’s what works-based on real programs that have saved lives.

  1. Reduce your dose by 25-30% during heatwaves. Your body isn’t processing the same way. What was safe last week might be dangerous today.
  2. Drink water-on a schedule. One cup (8 ounces) every 20 minutes. Not when you’re thirsty. Not when you feel like it. Every 20 minutes. Cool water, between 50°F and 60°F, is best. Avoid alcohol and caffeine-they make dehydration worse.
  3. Don’t use alone. Even if it feels risky to be around others, having someone there who knows how to use naloxone can mean the difference between life and death. If you’re using opioids, carry naloxone. Always.
  4. Find shade or cooling spaces. Libraries, community centers, and public transit stations are often air-conditioned. Many cities now have designated cooling centers that welcome people who use drugs. Check with local harm reduction groups-they know where they are.
  5. Monitor your body. Dizziness, nausea, confusion, or a rapid heartbeat aren’t just signs of heat exhaustion-they’re early signs of overdose risk. If you feel off, stop using. Rest. Hydrate. Wait.
A cool, safe community center offering water and naloxone to vulnerable people during a heatwave.

Community efforts that are actually working

Some places are getting this right.

In Philadelphia, public health workers hand out over 2,500 cooling kits each summer. Each one has electrolyte packets, misting towels, water bottles, and cards with overdose prevention info. Since 2020, heat-related overdose calls have dropped 17% in areas where these kits are distributed.

In Vancouver, they opened seven air-conditioned respite centers next to supervised consumption sites during the 2021 heat dome. Those centers didn’t just offer cool air-they offered food, water, medical checks, and naloxone. Overdose deaths dropped by 34% compared to previous years.

In Maricopa County, Arizona, volunteers trained in naloxone use made over 12,000 wellness checks during the 2022 heat season. They didn’t judge. They didn’t call the police. They asked: “Are you okay? Do you need water? Can I help you get to a cooler place?” They intervened in 287 overdoses.

Why most heat emergency plans fail people who use drugs

Only 12 out of 50 U.S. states include substance use in their official heat emergency plans. Most don’t even mention it. That’s a massive gap.

Health departments often assume people who use drugs will “just stay home” or “know better.” But when you’re homeless, or dealing with mental illness, or in withdrawal, “staying home” isn’t an option. And “knowing better” doesn’t matter when your body is failing from heat and drugs at the same time.

The CDC found that 18-22% of all heat-related emergency visits are from people who use drugs. Yet only 28% of city heat response plans even try to reach them.

What’s changing-and what you need to watch for

By 2050, the number of days each year above 24°C could increase by 20-30. That means more heatwaves. More overdose risks.

New research is showing that heat changes your gut microbiome-which could affect how drugs are broken down. That’s still being studied, but it means even long-term users might start reacting differently to the same doses.

The Biden administration just allocated $50 million to fix this. By December 2025, every state health department will be required to include overdose prevention in their heat emergency plans. That’s a big deal. But until then, you can’t wait for policy. You need to act now.

A rescuer helping an unconscious person on a hot sidewalk as ethereal heat spirits fade in the breeze.

What to do if you’re helping someone else

You don’t need to be a professional to make a difference.

  • Carry naloxone. Know how to use it. Teach the people around you.
  • If you see someone looking unwell in the heat, ask: “Do you need water? Can I help you get inside?” Don’t assume they’re fine. Don’t assume they’re using. Just ask.
  • Share info. Text a link to your local harm reduction group. Send someone the number for a cooling center.
  • Don’t report people to police for having water or cooling supplies. That’s what’s happening in some cities-and it’s killing people.

Heat doesn’t care if you’re sober. It doesn’t care if you’re in recovery. It doesn’t care if you’ve been using for 20 years. It only cares about your body’s limits. And right now, those limits are shrinking.

When to get help immediately

If someone is:

  • Confused or disoriented
  • Hot to the touch but not sweating
  • Having seizures or convulsions
  • Unconscious or not breathing

Call emergency services right away. Give naloxone if it’s an opioid overdose. Move them to shade or a cooler place. Cool them with water or wet cloths. Don’t wait. Don’t hesitate. This isn’t a judgment call. It’s a survival call.

Can heat make my drug use more dangerous even if I don’t feel hot?

Yes. Your body can be overheating even if you don’t feel it. Heat stress doesn’t always come with obvious symptoms like sweating or dizziness. It can sneak up, especially if you’re using stimulants or have a mental health condition. By the time you feel bad, your body is already struggling. That’s why reducing your dose and drinking water on schedule matters-even if you think you’re fine.

Is it safe to use drugs in air-conditioned places like malls or libraries?

Using drugs in public spaces is risky for many reasons, including legal consequences and safety. But if you’re in a heatwave and your only option is to be outside, being indoors-even if you’re not supposed to be there-is better than being exposed. Many harm reduction groups work with libraries and transit centers to create safer spaces during extreme heat. If you’re in a public space, stay hydrated, stay cool, and don’t use alone. Your safety matters more than rules that don’t protect you.

Why do some shelters turn away people who are using drugs during heatwaves?

Many shelters have policies that exclude people actively using drugs, often due to lack of staff training, fear of liability, or outdated rules. But during heatwaves, these policies become deadly. People who are turned away are forced to sleep on sidewalks or in cars-places where heat can kill faster than drugs alone. The best shelters now offer harm reduction services: naloxone, water, cooling stations, and non-judgmental care. If your local shelter doesn’t, ask them why-and push for change.

Can I still use naloxone if I’m not sure if it’s an opioid overdose?

Yes. Naloxone is safe to use even if opioids aren’t involved. It has no effect on stimulants like cocaine or meth. If someone is unresponsive, not breathing, or has blue lips, give naloxone. It won’t hurt them. It might save them. And if they’re using opioids, it’s the only thing that can reverse the overdose quickly enough.

Are there free cooling kits or hydration supplies available in my area?

Many cities now offer free cooling kits during heat emergencies. These often include electrolyte packets, misting towels, water bottles, and overdose prevention info. Contact your local health department, harm reduction center, or needle exchange program. If you’re in Brisbane, check with the Queensland Health Heatwave Response Team or local organizations like the Brisbane Drug and Alcohol Information Service. They’ll tell you where to get supplies-and they won’t ask for ID.

What if I’m on medication for mental health and I use drugs? Is it safe during heat?

It’s not safe. Medications like antipsychotics and antidepressants can reduce your body’s ability to handle heat. They can also interact dangerously with drugs like cocaine or MDMA. If you’re on these meds, your risk of heatstroke and overdose is much higher. Talk to your doctor before the next heatwave. Ask: “Should I adjust my dose?” “What signs should I watch for?” Don’t wait until you’re in crisis.

Is it true that heat can change how drugs work in my body?

Yes. Heat increases your heart rate, dehydrates you, and changes how your liver and kidneys process drugs. This can make a familiar dose much stronger than usual. New research also suggests heat might change your gut bacteria, which affects drug metabolism. That means even if you’ve used the same drug the same way for years, your body’s response could change during a heatwave. Play it safe: reduce your dose, hydrate, and don’t use alone.

Next steps: What to do right now

If you use drugs:

  • Get naloxone today. Even if you don’t use opioids-someone you know might.
  • Find your nearest cooling center or harm reduction service. Save the number.
  • Start drinking water on a schedule. One cup every 20 minutes, even if you’re not thirsty.
  • Reduce your dose by 25-30% if temperatures are above 24°C.

If you care about someone who uses drugs:

  • Ask them: “Do you have water? Do you have a plan for the heat?”
  • Carry naloxone with you. Learn how to use it.
  • Don’t report them. Help them.

Heat doesn’t wait for perfect conditions. Neither should you.