When the temperature hits 90°F and the air feels thick, most people think about staying cool, drinking water, and avoiding the sun. But for people who use drugs, extreme heat isn’t just uncomfortable-it’s deadly. Heatwaves don’t just raise body temperature; they raise the risk of overdose. And it’s not just about being outside. Even indoors without AC, the body struggles to process drugs the same way it does in cooler weather. This isn’t theoretical. In cities like Seattle, where summer heat used to be rare, overdose deaths spiked by 37% during the 2021 heat dome. People didn’t use more drugs-they just couldn’t handle what they already had.

Why Heat Makes Overdose More Likely

Your body works hard to stay at 98.6°F. When it’s hot outside, your heart pumps faster to move blood to the skin and cool you down. That’s normal. But if you’ve taken stimulants like cocaine or meth, your heart is already racing. Heat adds extra strain-up to 25 more beats per minute on top of a 40% increase from the drug. That’s a recipe for heart attack or stroke.

Dehydration makes it worse. When you sweat, you lose fluids. Even a 2% drop in body water can concentrate drugs in your bloodstream by 15-20%. That means a dose you’ve taken safely before now hits like a stronger dose. It’s like drinking the same amount of alcohol on an empty stomach after a long hike. Your body can’t adjust fast enough.

Opioids are just as dangerous. Heat slows down your body’s ability to breathe deeply and regularly. Opioids already suppress breathing. When you’re overheated, that suppression gets stronger. A 2022 study found that core body temperature rises of just 1.5°C can reduce respiratory compensation by up to 18%. That’s the difference between breathing okay and stopping altogether.

And it’s not just the drugs. Many people take medications for mental health-antidepressants, antipsychotics, or blood pressure pills. About 70% of antipsychotics and 45% of antidepressants become less effective or more toxic in heat. That means someone managing depression or schizophrenia might feel worse, use more drugs to cope, and not realize their body is breaking down.

Who’s Most at Risk

You don’t have to be homeless to be in danger. But homelessness increases risk dramatically. About 38% of people experiencing homelessness have a substance use disorder. They’re more likely to be outside, without water, without shade, and without access to cool spaces. In 2020, over half a million people in the U.S. were homeless on any given night. During heatwaves, many shelters turn people away if they’re actively using drugs. Some police departments even confiscate cooling supplies-misting towels, electrolyte packets-because they don’t understand they’re life-saving tools, not drug paraphernalia.

People with chronic conditions-heart disease, kidney problems, diabetes-are also at higher risk. Heat stresses the body. If your organs are already working hard, adding drugs into the mix can push them over the edge.

And here’s something many don’t realize: places that rarely see heat, like the Pacific Northwest, see the biggest spikes in overdose risk. Why? Because people there aren’t acclimated. Their bodies haven’t learned how to cope. In Arizona, where it’s hot every summer, the overdose increase during heatwaves is about 2.1 times normal. In Seattle or Portland, it’s up to 3.7 times higher.

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 saved lives.

• Reduce your dose by 25-30% during heatwaves. Your body processes drugs differently when it’s hot. What felt safe last week might kill you now.
• Drink water-on a schedule. Don’t wait until you’re thirsty. Drink one cup (8 oz) every 20 minutes. Cool water, between 50-60°F, is best. Avoid alcohol, caffeine, or sugary drinks-they make dehydration worse.
• Use a buddy system. Never use alone. If you feel dizzy, nauseous, or confused, stop. Your friend can call 911 or give naloxone if needed. Naloxone doesn’t reverse stimulant overdoses, but it can save lives in mixed-drug situations.
• Find a cool space. Libraries, community centers, malls, and public transit stations often have AC. Some cities now offer free cooling centers with trained staff who won’t call the police. Ask local harm reduction groups where they are.
• Use cooling tools. Wet a towel, put it on your neck or wrists. Use a fan. If you have ice packs, wrap them in cloth and press them to your armpits or groin. These spots have major blood vessels-cooling them lowers core temperature fast.

What Service Providers Should Do

Harm reduction organizations, clinics, and outreach workers are on the front lines. They need to act before people die.

• Distribute cooling kits. These should include electrolyte packets, small misting bottles, cooling towels, and clear printed instructions. Philadelphia gives out 2,500+ kits every summer. They’ve seen a 17% drop in heat-related overdose calls.
• Train staff on heat risk screening. Use tools like the CHILL’D-Out questionnaire. It asks about housing, meds, heart conditions, and drug use. If someone checks three or more boxes, they need extra support.
• Partner with cooling centers. Vancouver’s program co-located air-conditioned respite centers with supervised consumption sites. During the 2021 heat dome, heat-related overdose deaths dropped by 34%.
• Advocate for policy change. Only 12 out of 50 U.S. states include drug users in their official heat emergency plans. That has to change. If your city doesn’t have a plan, push for one. Use data: people who use drugs make up 18-22% of heat-related ER visits.

What’s Changing-and What’s Coming

Climate change isn’t slowing down. By 2050, the U.S. could see 20-30 more days each year above the 24°C (75°F) threshold where overdose risk spikes. The CDC and WHO now recognize this as a public health emergency. The Biden administration allocated $50 million in 2023 to force states to include overdose risk in heat response plans by December 2025.

New research is emerging too. Scientists are finding that heat changes the gut microbiome-which affects how drugs are broken down. That could mean future harm reduction advice will need to include dietary tips, not just hydration.

For now, the tools we have work. Hydration. Lower doses. Cool spaces. Buddy systems. Naloxone. These aren’t new ideas. But in heatwaves, they’re life-or-death.

What to Do If Someone Overdoses in the Heat

If someone collapses, isn’t breathing, or is unresponsive:

1. Call 911 immediately. Say: “I think this is an overdose, and it’s hot-this person may be overheated.”
2. Start CPR if they’re not breathing. Push hard and fast on the center of the chest.
3. If you have naloxone, give it. Even if the drug isn’t an opioid, it won’t hurt-and it might help if the person used mixed drugs.
4. Move them to a cooler place. Take off excess clothes. Wet their skin with water. Fan them.
5. Stay with them until help arrives. Heat and overdose together make recovery slower. They need monitoring.

Don’t wait for symptoms to get worse. Heat makes things move fast. A person who seemed fine 10 minutes ago can stop breathing in under a minute.

Next Steps: What to Do Today

If you use drugs:

• Check your local health department’s website for heat advisories.
• Call a harm reduction hotline or drop-in center. Ask: “Where are the cool places?”
• Get naloxone if you don’t have it.
• Text a friend: “If I don’t respond in an hour, check on me.”
• Reduce your dose-even a little-until the heat passes.

If you’re a friend, family member, or provider:

• Don’t assume someone’s fine because they’re not overdosing.
• Ask: “Are you staying cool? Are you drinking water?”
• Carry naloxone. Know how to use it.
• Push your city to include drug users in heat emergency plans.

Heat doesn’t care who you are. But your choices can still save your life-or someone else’s.