How to Manage Overdose Risk During Heatwaves and Illness

Heatwaves don’t just make you sweaty-they can kill you faster if you use drugs.

When the temperature hits 24°C (75°F) or higher, the risk of an accidental overdose spikes-especially for people using stimulants like cocaine, methamphetamine, or even opioids. It’s not just about dehydration. It’s about your body losing its ability to cope. Your heart is already working harder. Your brain’s judgment is clouded. And if you’re homeless, or on medication for mental health, or just trying to get through another day-you’re not just at risk. You’re in danger.

In Melbourne, where summer temperatures regularly climb past 30°C, this isn’t theoretical. In 2022, emergency services saw a 22% jump in overdose calls during heat advisories. The same pattern shows up in New York, Philadelphia, and Phoenix. It’s happening everywhere. And most people don’t know why.

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 blood flow to your skin, and raising your heart rate. That’s normal. But if you’re using drugs, your body is already under stress.

Stimulants like cocaine and meth push your heart rate up by 30-50%. Heat adds another 10-25 beats per minute. Together, that’s a cardiac overload. Your heart can’t keep up. That’s how people collapse-even if they’ve used the same dose for years.

Dehydration makes it worse. Lose just 2% of your body weight in fluids-about one liter for an average adult-and your blood gets thicker. Drugs concentrate in your bloodstream. What used to be a safe dose suddenly becomes a lethal one. Studies show this can increase drug concentration by 15-20%.

For opioids, heat reduces your body’s ability to compensate for slowed breathing. Normally, your body tries to breathe faster when oxygen drops. Heat shuts that down by 12-18%. You might not even realize you’re suffocating until it’s too late.

And it’s not just street drugs. Medications for depression, anxiety, or psychosis can lose effectiveness-or become more toxic-in extreme heat. Up to 70% of antipsychotics and 45% of antidepressants behave differently when it’s hot. That means someone managing their mental health could suddenly feel worse, use more drugs to cope, and overdose without understanding why.

Who’s most at risk-and why

It’s not random. Certain groups face a perfect storm of risk.

• People experiencing homelessness: Around 38% have substance use disorders. They have no air conditioning, no access to clean water, and often sleep on concrete that radiates heat overnight.
• People on multiple medications: Mixing mental health meds with drugs or alcohol increases heat sensitivity. Many don’t know their meds are making them more vulnerable.
• People in cooler climates: Cities like Seattle or Portland see a steeper rise in overdose deaths during heatwaves than Phoenix or Las Vegas. Why? Their bodies haven’t adapted. They’re less likely to recognize early signs of heat illness.
• People who use alone: Isolation is deadly. If you collapse and no one’s around, no one calls for help.

One study found that 35% of people admitted for heat illness during emergencies also had a substance use disorder. That’s not coincidence. That’s a system failure.

What to do: Practical harm reduction steps

You don’t need to stop using drugs to stay alive. You just need to adjust.

1. Reduce your dose by 25-30% when it’s over 24°C. Your body isn’t the same in the heat. What worked last week might kill you today.
2. Hydrate constantly. Drink one cup (8 oz) of cool water every 20 minutes-even if you’re not thirsty. Avoid alcohol and caffeine. They make dehydration worse.
3. Stay in the shade or air-conditioned spaces. Libraries, community centers, and public pools are safe options. If you’re offered a cooling center, go. It’s not judgment. It’s survival.
4. Use with someone. Never use alone. Have a buddy who knows how to use naloxone and can call for help if things go wrong.
5. Carry naloxone. It saves lives from opioid overdoses. Keep it with you. Make sure your friends know where it is.
6. Wear light clothing and use cooling tools. Misting towels, damp bandanas, and portable fans help. Some harm reduction groups give them out for free.

These aren’t just suggestions. They’re evidence-based. In New York, outreach workers who handed out water and cooling packs saw a 17% drop in heat-related overdose calls. In Vancouver, cooling centers next to supervised injection sites cut overdose deaths by 34% during the 2021 heat dome.

What services are available-and where to find them

Not every city has a plan. But some do.

In Philadelphia, public health teams hand out over 2,500 cooling kits each summer. Each one has electrolyte packets, water bottles, misting towels, and info on overdose prevention. In Maricopa County, Arizona, volunteers trained in naloxone do door-to-door wellness checks during heatwaves. They’ve made over 12,000 visits in a single season-and saved hundreds of lives.

Here’s how to find help:

• Call your local health department. Ask: “Do you have a heat emergency plan that includes people who use drugs?”
• Check with needle exchange programs. They often have cooling supplies and can connect you to safe spaces.
• Look up “harm reduction center near me.” Many offer free water, showers, and rest during extreme heat.
• If you’re on medication, talk to your doctor about how heat affects your prescription. Don’t assume it’s safe.

Some shelters still turn away people who are actively using. That’s wrong. And it’s deadly. If you’re turned away, ask for a referral to a medical respite center or a supervised consumption site. They’re legally required to provide care during emergencies in many places.

The bigger picture: Why this isn’t just about individual choices

This isn’t a personal failure. It’s a policy failure.

Only 12 out of 50 U.S. states have official heat emergency plans that include people who use drugs. Most don’t train first responders to recognize the link between heat and overdose. Many police departments still confiscate water or cooling supplies from outreach workers.

Climate change is making this worse. By 2050, we could see 20-30 extra days each year above the 24°C overdose risk threshold. That’s not a future problem. It’s happening now.

The Biden administration just allocated $50 million to fix this. States must have overdose risk protocols in their heat plans by December 2025. That’s progress. But it’s not enough. Communities need to act now.

What you can do today

You don’t need to be an expert. You just need to care.

• If you know someone who uses drugs, check in during heatwaves. Ask: “Are you cool? Have you eaten? Have you drunk water today?”
• Donate to local harm reduction groups. They need water, electrolytes, and cooling towels more than you know.
• Advocate. Tell your city council: “Include people who use drugs in your heat emergency plan.”
• If you’re a healthcare worker, screen for heat risk. Use tools like the CHILL’D-Out questionnaire. Ask about housing, meds, and drug use. Don’t assume they’re fine.

Overdose deaths during heatwaves aren’t inevitable. They’re preventable. But only if we act.

What’s next?

If you’re reading this, you’re already ahead of most people. You know heat and drugs are a deadly mix. Now, share this. Talk to someone who uses drugs. Tell your local council. Donate to a harm reduction group. Keep water in your car. Check on your neighbor.

Survival isn’t about willpower. It’s about preparation. And community. And knowing when to ask for help.