How to Manage Overdose Risk During Heatwaves and Illness

Heatwaves Don’t Just Make You Sweat-They Can Kill

When the temperature hits 24°C (75°F) or higher, your body starts working harder just to stay cool. For most people, that means drinking more water, turning on the fan, or heading indoors. But for someone using drugs, that same heat can turn a routine use into a life-threatening emergency. Overdose risk doesn’t just rise with dosage-it rises with the weather.

In New York City, emergency responders saw a 22% spike in overdose calls during heat advisories between 2018 and 2022. In Arizona, during the 2021 heat dome, overdose deaths climbed faster than in any previous summer. This isn’t coincidence. It’s biology.

Why Heat Makes Drugs More Dangerous

Your body is a finely tuned machine. When it gets hot, it tries to cool down by sweating, increasing heart rate, and redirecting blood flow. But many drugs interfere with those natural processes.

Stimulants like cocaine and methamphetamine already push your heart rate up by 30-50%. Add heat, and that increase jumps another 10-25%. Your heart doesn’t just work harder-it starts to fail. Dehydration from heat concentrates drugs in your bloodstream. Lose just 2% of your body weight in fluids, and drug levels in your blood can spike by 15-20%. That’s like taking a second dose without realizing it.

Opioids are no safer. Heat reduces your body’s ability to compensate for slowed breathing-a key danger with opioids. Studies show respiratory compensation drops by 12-18% during heat exposure. That tiny margin between safety and suffocation disappears fast.

And it’s not just the drugs. Many medications for mental health-70% of antipsychotics and 45% of antidepressants-become less effective or more toxic in high heat. If you’re on one of these and using drugs, your body has even less ability to cope.

Who’s Most at Risk?

People experiencing homelessness make up just 0.1% of the U.S. population-but they account for 38% of those with substance use disorders, according to SAMHSA. They’re also the least likely to have access to air conditioning, clean water, or shade.

Heatwaves hit cities hardest. Urban areas can be 3-5°C hotter than nearby suburbs because of concrete, asphalt, and lack of trees. If you’re sleeping on a sidewalk in Sydney, Melbourne, or Philadelphia, you’re not just dealing with the sun-you’re in a heat trap.

And here’s the cruel twist: many shelters turn people away if they’re actively using drugs. So even when the heat is deadly, safety isn’t guaranteed. In some cities, outreach workers have had cooling supplies confiscated by police. This isn’t just negligence-it’s systemic abandonment.

What You Can Do: Practical Harm Reduction Steps

You don’t need a clinic or a doctor to lower your risk. You just need to change your behavior during hot weather.

1. Reduce your dose by 25-30% when temperatures climb above 24°C. Your body processes drugs differently in heat. What’s safe on a 20°C day might be lethal on a 32°C day.
2. Hydrate before, during, and after. Drink one cup (8 oz) of cool water every 20 minutes. Don’t wait until you’re thirsty. Thirst means you’re already dehydrated. Avoid alcohol and caffeine-they make dehydration worse.
3. Never use alone. If you’re alone and you overdose, no one finds you. Find a buddy. Even if they’re not using, they can call for help, stay with you, or administer naloxone.
4. Carry naloxone and know how to use it. Naloxone saves lives. Keep it in your pocket, your bag, your car. If you’re using opioids, this isn’t optional. It’s survival.
5. Find shade or cooling centers. Libraries, community centers, and some pharmacies offer free air-conditioned space during heat alerts. In Vancouver, co-located respite centers near supervised consumption sites cut heat-related overdose deaths by 34% in 2021. Ask local harm reduction groups where to go.
6. Don’t rely on feeling ‘fine.’ Heat reduces your judgment by 25-35%. You won’t know you’re in danger until it’s too late. If you’re dizzy, nauseous, or confused, stop. Rest. Cool down. Call someone.

What Communities and Services Can Do

Individual action isn’t enough. Systems need to change.

Philadelphia now hands out over 2,500 cooling kits each summer: electrolyte packets, misting towels, water bottles, and info cards. NYC’s Harm Reduction Coalition saw a 17% drop in heat-related overdose calls after training staff to offer water and hydration reminders during outreach.

In Maricopa County, Arizona, volunteers trained in naloxone use made over 12,000 wellness checks during the 2022 heat season. They found people passed out on sidewalks, in cars, under bridges. They saved lives.

But only 12 out of 50 U.S. states include drug users in their official heat emergency plans. That’s a failure. The CDC says people who use drugs make up 18-22% of heat-related ER visits. Yet most heat response plans don’t mention them at all.

By December 2025, U.S. states are required-by federal order-to include overdose risk protocols in their heat action plans. That’s progress. But it’s not enough. We need this everywhere: Australia, Canada, Europe. We need cooling centers that don’t ask questions. We need water stations on every block. We need policies that say: if you’re struggling, you deserve shelter, water, and safety-no matter what.

What’s Coming Next

Climate change isn’t slowing down. By 2050, there could be 20-30 more days each year above the 24°C overdose risk threshold. That means more heatwaves. More deaths. More grief.

Researchers are now looking at how heat changes the gut microbiome-and whether that affects how drugs are processed. Early data shows a 15-20% shift in bacterial activity during heat exposure. That could mean new warnings: avoid certain drugs on hot days, adjust doses differently based on climate zones.

For now, the science is clear: heat kills faster when drugs are involved. The tools to prevent it already exist. What’s missing is the will.

What to Do Right Now

If you use drugs:

• Check the weather forecast every morning. If it’s above 24°C, assume your body is under more stress than usual.
• Carry water. Always.
• Carry naloxone. Always.
• Call a friend before you use. Stay in contact.
• If you feel off-dizzy, nauseous, heart racing-stop. Sit down. Cool off. Don’t push through it.

If you know someone who uses drugs:

• Ask them if they’ve thought about heat safety.
• Give them water, a hat, shade.
• Teach them how to use naloxone. Practice with a trainer kit.
• Know where the nearest cooling center is. Share the info.

If you work in health, outreach, or social services:

• Include heat risk in your harm reduction materials.
• Train staff to recognize signs of heat stress in people who use drugs.
• Partner with local agencies to distribute cooling supplies.
• Push your city to include drug users in heat emergency plans.

This isn’t about judgment. It’s about survival. When the sun beats down, the body doesn’t care if you’re addicted, homeless, or struggling. It just needs water, shade, and time. We owe it to each other to make sure those things are available.