Does extreme heat affect people with chronic conditions differently?

Yes. Extreme heat poses elevated risk for people managing heart disease, diabetes, kidney disease, and lung conditions. NYC Health Department data shows that 89% of heat-stress deaths involved at least one chronic health condition. CDC identifies certain daily medications — including some blood-pressure medicines, diuretics, antihistamines, and antipsychotics — as factors that can affect the body’s ability to regulate temperature in heat. A brief conversation with a pharmacist or prescribing clinician before peak summer is one of the most effective prevention steps for anyone who takes daily medications.

Summer Heat and Chronic Conditions: What to Know If You Manage Diabetes, Heart Disease, or Take Daily Medications

Heat exposure is one of the leading causes of weather-related death in the United States (CDC). More than two-thirds of Americans were under heat alerts in 2023. But the risk is not distributed equally.

For most healthy adults, summer heat is uncomfortable. For people managing heart disease, diabetes, kidney conditions, lung disease, or taking certain daily medications, the same temperatures can trigger medical emergencies. NYC Health Department’s 2025 heat mortality report found that 89% of heat-stress decedents had at least one chronic health condition — most commonly cardiovascular disease, lung conditions, and diabetes.

This blog is specifically for people whose health conditions or medications change how their body responds to heat — and for the coworkers, family members, and caregivers who look out for them.

Who’s Most Affected — and Why Heat Hits Harder

CDC identifies several groups at elevated risk during extreme heat:

• People with cardiovascular disease. Heat forces the heart to work harder, pumping blood toward the skin surface for cooling. CDC’s clinical guidance notes that hot days increase the risk of heart attacks, strokes, arrhythmias, and worsened heart failure. Poor air quality during heat waves compounds cardiovascular risk further.
• People with diabetes. Heat can affect blood sugar regulation and accelerate dehydration. High temperatures can also damage insulin and glucose monitoring equipment.
• People with kidney disease. Dehydration from heat stresses the kidneys. HHS notes that repeated or untreated heat-related dehydration can cause kidney injury — and some damage can become irreversible.
• People with lung conditions (asthma, COPD). Heat increases ground-level ozone production, and hot polluted air worsens respiratory conditions. CDC recommends checking the air quality index alongside the heat index.
• Older adults (65+). Age-related changes in thermoregulation, combined with higher rates of chronic conditions and medication use, place older adults in the highest-risk category.

These risk factors compound. A 68-year-old taking a diuretic for blood pressure who also has early-stage kidney disease faces a qualitatively different heat risk than a healthy 35-year-old. The standard “drink water and find shade” advice applies — but for this population, it may not be sufficient on its own.

The Medication Connection — The Factor Most People Don’t Think About

Many people don’t realize that daily medications can change how their body handles heat. CDC and HHS identify several medication categories that may affect heat response:

Critical message: never stop or adjust a prescribed medication because of heat without talking to your doctor or pharmacist first. The risk of stopping a needed medication is typically far greater than the heat-related risk the medication may contribute to. The goal of this section is awareness — knowing that your medications may change your heat equation — not self-management.

Diabetes and Heat — What Changes When Temperatures Rise

People managing diabetes face a specific set of heat-related concerns that go beyond general summer safety.

Blood Sugar and Heat

Heat can affect blood sugar levels in ways that are difficult to predict. Some people experience drops; others experience rises. The mechanism involves changes in how the body absorbs insulin, shifts in activity levels and appetite, and the dehydrating effect of heat. Many clinicians discuss increasing monitoring frequency during heat waves with their patients who manage diabetes.

Insulin and Equipment Storage

Insulin degrades in high temperatures. It should not be left in a hot car, in direct sunlight, or in any environment above its recommended storage range. Once insulin has been compromised by heat, it may not work effectively — and the reduced effectiveness may not be immediately obvious. Glucose monitors, continuous glucose monitors (CGMs), and test strips can also be affected by extreme temperatures. Following manufacturer storage and operating guidelines during summer months is especially important.

Dehydration Risk

People with diabetes may be more susceptible to dehydration, which can affect blood sugar readings and kidney function. Consistent hydration — with water, not sugary or caffeinated drinks — is particularly important during hot weather.

If you manage diabetes, summer heat adds variables to your daily routine. Your endocrinologist, diabetes educator, or pharmacist can help you plan for them before temperatures peak.

Practical Protection — What CDC Recommends

• Hydrate consistently. Don’t wait for thirst. Water is the primary recommendation. Avoid alcohol and drinks with high sugar or caffeine content, which can worsen dehydration.
• Stay cool during peak hours (10 a.m.–4 p.m.). Air-conditioned environments are the most effective protection. If home AC is unavailable, cooling centers, libraries, and shopping centers provide relief during the hottest hours.
• Check the heat forecast AND the air quality forecast. CDC specifically recommends checking both together. Poor air quality during heat waves compounds cardiovascular and respiratory risk. The AQI and CDC HeatRisk tools are available on weather apps and at weather.gov.
• Store medications properly. Keep medications out of hot cars, direct sunlight, and non-climate-controlled spaces. For medications requiring refrigeration (insulin, certain biologics), develop a plan for heat-related power outages.
• Wear lightweight, light-colored, loose-fitting clothing. Standard guidance, but more consequential for people whose thermoregulation is already affected by a condition or medication.
• Know your personal risk equation. Your conditions + your medications + your environment. The intersection of all three determines your actual risk level in heat.

Warning Signs — When Heat Becomes a Medical Emergency

The distinction between heat exhaustion and heat stroke matters for everyone. It’s especially critical for people with chronic conditions because progression from exhaustion to stroke can happen faster when the body’s cooling system is already compromised.

Heat stroke is a medical emergency. Call 911. For people with chronic conditions, a lower threshold for seeking medical attention is appropriate. Symptoms that might resolve on their own in a healthy adult can progress more quickly when complicated by cardiovascular disease, diabetes, or medication effects.

(For the full comparison including detailed response steps, see our guide to heat exhaustion vs. heat stroke at work.)

For Teams, Caregivers, and Neighbors

• Check on higher-risk people during heat waves. Older adults, people living alone, and people managing chronic conditions may not recognize heat-stress symptoms in themselves — especially if confusion is an early sign.
• At work: If you supervise a team that includes workers managing chronic conditions, standard heat-safety protocols apply with heightened attention. Indoor breaks, hydration access, and peer monitoring become more critical for this population.
• At home: A daily phone call or visit during extreme heat events takes two minutes and can catch a developing problem before it becomes an emergency. NYC data shows that many heat-stress deaths occur at home, in people who were alone and without working AC.
• Know who around you is higher-risk. A neighbor on blood pressure medication. A parent managing diabetes. A coworker with asthma. Heat illness often becomes visible to others before the person experiencing it recognizes what’s happening.

The Two-Minute Pharmacist Conversation

If you take daily medications, this is the single highest-value prevention step you can take before summer peaks.

Walk up to any pharmacy counter and ask four questions:

• 1. Do any of my medications affect how my body handles heat?
• 2. Should I adjust my hydration approach during heat waves?
• 3. Are there storage concerns I need to plan for this summer?
• 4. What symptoms should I watch for that are specific to my situation?

This conversation takes two minutes. It’s free. It’s available at any pharmacy. And it produces personalized guidance that a general blog cannot — because a pharmacist can see your specific medication list and flag the interactions that apply to you.

A two-minute conversation now can prevent a trip to the ER in August. That’s the logic of prevention: small investment, large payoff, measured in problems that never happen.

The Bottom Line

Summer heat is uncomfortable for most people. For those managing chronic conditions or taking daily medications, it can be dangerous. The risk factors are well-documented (CDC, HHS), the warning signs are recognizable, and the prevention steps are practical and accessible.

The two things that matter most: know that your conditions and medications may change your heat equation, and have a brief conversation with your pharmacist or doctor before temperatures peak. Everything else — hydration, shade, monitoring, medication storage — flows from that awareness.

And look out for the people around you. A two-minute check-in with a neighbor, a parent, or a coworker during a heat wave costs nothing and can catch something serious before it becomes an emergency.

Frequently Asked Questions

Does extreme heat affect people with chronic conditions differently?

Yes. CDC identifies people with cardiovascular disease, diabetes, kidney disease, and lung conditions as being at elevated risk during extreme heat. NYC Health Department data shows that 89% of heat-stress deaths involved at least one chronic condition. The body’s cooling mechanisms can be compromised by both the underlying condition and by certain medications used to manage it.

Can daily medications increase heat sensitivity?

Certain medication categories can affect the body’s temperature regulation in heat. CDC and HHS identify diuretics, some blood pressure medicines, antihistamines, some antidepressants and antipsychotics, and stimulants as categories that may affect sweating, hydration, or heat awareness. Never stop or adjust a medication because of heat without consulting your prescriber.

How does heat affect blood sugar in people with diabetes?

Heat can affect blood sugar levels unpredictably — some people experience drops, others experience rises. Heat also accelerates dehydration, which can affect blood sugar readings. Insulin and glucose monitors can be damaged by high temperatures. People managing diabetes may benefit from increased monitoring frequency during heat waves, in consultation with their healthcare provider.

What should people with heart disease do during heat waves?

CDC recommends that people with cardiovascular disease check the HeatRisk forecast and the air quality index daily during warm months. Hot days increase the risk of heart attacks, strokes, and arrhythmias. Poor air quality compounds the risk. Stay in air-conditioned environments during peak hours, hydrate consistently, and discuss any medication concerns with a clinician before heat season.

How should medications be stored in summer heat?

Medications should be kept out of hot cars, direct sunlight, and non-climate-controlled spaces. Medications requiring refrigeration (including insulin and some biologics) need a plan for heat-related power outages. CDC recommends discussing proper medication storage with your pharmacist, particularly for medications you carry during outdoor activities.

Key Takeaways

• Heat exposure is a leading cause of weather-related death in the U.S. NYC data shows 89% of heat-stress deaths involved at least one chronic health condition — most commonly cardiovascular disease, lung conditions, and diabetes.
• Certain daily medications — including diuretics, some blood pressure medicines, antihistamines, and some psychiatric medications — can affect the body’s ability to regulate temperature in heat. Never stop a medication because of heat without consulting your prescriber.
• Heat can affect blood sugar levels, insulin effectiveness, and glucose monitor accuracy. People managing diabetes may need to increase monitoring and store supplies carefully during summer.
• CDC recommends checking both the heat forecast AND the air quality index — poor air quality during heat waves compounds cardiovascular and respiratory risk.
• A two-minute pharmacist conversation before peak summer is the highest-value prevention step for anyone taking daily medications. Four questions can produce personalized guidance that a general article cannot.
• Check on higher-risk people during heat waves. Older adults, people living alone, and those managing chronic conditions may not recognize symptoms — especially when confusion is an early sign.

Published by LifeX Research Corp. LifeX Research Corporation is a health data research organization that analyzes real-world health trends and population health patterns. The organization operates in connection with an ERISA-governed, self-funded employee benefit plan and does not sell, market, broker, or underwrite health insurance.