By Nachiket J. Patel, MD, FACC, FSCAI.
A heart medication that is appropriate in January can still be appropriate in July. What changes is the environment. Prolonged heat can increase cardiovascular demand and promote dehydration and electrolyte imbalance. Heat and some medications can also affect blood pressure, kidney blood flow, fluid balance, or the body’s ability to cool itself.[1][2]
The wrong response is to guess. CDC advises patients not to abruptly stop any medication without a plan. A medicine prescribed to control blood pressure, heart rhythm, fluid buildup, or clotting may be providing important protection even on a hot day.[1]
The safer approach is to decide in advance what to monitor, when to call, and whether any change is appropriate for you.
Which medicines need extra attention in hot weather?
Diuretics such as furosemide or hydrochlorothiazide increase salt and water loss. In the heat, that can contribute to dehydration, electrolyte changes, dizziness, fainting, or kidney stress. Yet a person with heart failure may still need the diuretic to prevent congestion.[1][3]
Several blood-pressure and heart-failure medicines can add to a heat-related drop in blood pressure. These include ACE inhibitors, ARBs, ARNIs, beta blockers, calcium-channel blockers, and nitrates. If you also take a diuretic, ask which symptoms or readings should prompt a call.[1]
Other prescriptions and over-the-counter products can matter too. Dehydration can cause some medicines to remain in the body longer. Nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen can add kidney stress when blood flow to the kidneys has already fallen. Sedating medicines and some antihistamines can reduce heat awareness or interfere with cooling.[1]
This is not a list of medicines to stop. It is a list of reasons to make an individualized plan.
Why “drink more water” is not the right answer for everyone
General heat advice often says to drink more water. That may be appropriate, but people with heart failure, kidney disease, or a prescribed fluid or sodium limit need individualized instructions.
Automatically increasing water, sports drinks, electrolyte powders, salt, or salt tablets may be unsafe for some patients. Extra sodium can worsen fluid retention, swelling, and blood pressure.
Ask how much fluid to drink each day and whether that amount should change during extreme heat, prolonged sweating, vomiting, or diarrhea. Follow the fluid, sodium, and daily-weight instructions from your care team.[2][3]
Before changing anything: a practical checklist
- Keep one current medication list. Include exact doses, timing, the reason for each medicine, over-the-counter pain relievers, sleep aids, antihistamines, and supplements.
- Ask which medicines make dehydration or low blood pressure more important for you. Risk depends on the combination of medicines, heart and kidney function, age, baseline blood pressure, and how much time you spend outside.
- Get specific monitoring instructions. Know whether to check blood pressure, pulse, daily weight, or another measure; what change should prompt a call; and which symptoms are an emergency.
- Write down your fluid instructions. Confirm your usual range, any restriction, whether electrolyte drinks are appropriate, and what to do during vomiting, diarrhea, or poor fluid intake.
- Create a heat-day and sick-day plan. Ask whether a medicine should ever be held, exactly when to call before holding it, and when it should be restarted. Do not improvise from advice written for someone else.
- Reduce the exposure first. Check the CDC HeatRisk forecast, move activity to cooler hours, use air conditioning or a cooling center, and arrange a check-in if you live alone.
- Protect the medicine itself. Follow the storage instructions on the label. Do not leave pills, insulin, inhalers, or medication devices in a parked car.[1]
Symptoms that deserve prompt attention
Headache, nausea, dizziness, weakness, heavy sweating, thirst, muscle cramps, or decreased urination can signal heat exhaustion. Move to a cool place, stop activity, and begin cooling. Contact your clinician promptly if symptoms do not improve or if you have heart or kidney disease.[2][4]
Contact your clinical team for repeated dizziness, near-fainting, unusually low blood pressure with symptoms, vomiting, markedly reduced urination, a rapid weight change, worsening leg swelling, or new shortness of breath. These findings can reflect heat illness, medication effects, heart failure, kidney stress, or more than one problem at once.[2][3]
Note when the symptoms began, how long you were in the heat, what you drank, whether you had vomiting or diarrhea, and what your blood pressure, pulse, or weight showed. These details help the clinical team distinguish heat exposure, medication effects, heart failure, and kidney stress.
When to call 911
Confusion, unusual behavior, slurred speech, seizure, collapse, loss of consciousness, or very high body temperature can indicate heat stroke. The skin may be hot and dry, or the person may still be sweating. Call 911. While waiting, move the person to a cooler place, remove outer clothing, and begin cooling with cool water or wet cloths. Do not give a suspected heat-stroke victim anything to drink.[4][5]
Also call 911 for new chest pain or pressure, severe or rapidly worsening shortness of breath, facial droop, arm weakness, speech difficulty, seizure, or loss of consciousness. Do not assume a cardiac emergency is “just the heat.”[2]
Dr. Patel’s Bottom Line
What I want patients to remember is simple: a hot day is a reason to plan, not improvise. Continue medications as directed unless you already have specific instructions for heat, illness, low blood pressure, or dehydration. If symptoms or home readings change, call before changing a medication, fluid target, or sodium plan. The safest plan protects against dehydration without losing the benefit of the treatment you were prescribed.
Sources and Further Reading
- CDC: Heat and Medications—Guidance for Clinicians, September 18, 2025.
- CDC: Clinical Overview of Heat and Cardiovascular Disease, September 18, 2025.
- American Heart Association: Lifestyle Changes for Heart Failure, reviewed June 16, 2025.
- CDC/NIOSH: Heat-related Illnesses, March 3, 2026.
- American Heart Association: Protect Your Heart in the Heat, reviewed January 11, 2024.
Related heart and vascular information
Schedule an appointment
If heat is repeatedly causing dizziness, low blood-pressure readings, swelling, or difficulty managing a heart medication, request an appointment with Flow Heart & Vascular in Mesa, Arizona. Call 911 for emergency symptoms.
This article provides general education and does not replace individualized medical advice. Do not change a medication, fluid restriction, or sodium plan based only on this website.
