This summer’s heat “dome” is brutal and could be deadly. Almost 80 million people in the US are living under heat warnings this week. While most people likely know the importance of staying hydrated, many likely don’t know the risks of the medicines they take.
Basic safety tips include avoiding caffeinated drinks and alcohol. But did you know that sugary drinks can also cause dehydration? Be careful when you reach for that cool, refreshing soda!
One study of heat-induced dehydration in animals showed that rehydration with a soft drink beverage worsened kidney injury compared to water or fluid with stevia, a plant-based sweetener. This was prompted, in part, by the epidemic of chronic kidney disease in sugarcane (and other) workers associated with heat-associated dehydration.
In addition to water, fruits and vegetables can help you meet your fluid needs. These include watermelon (92% water), strawberries (91%), canteloupe (90%), peaches (89%), oranges (88%), cucumber (95%), lettuce (96%), zucchini (94%), and celery (95%), among others. Interestingly, cottage cheese also has an 80% water content, and skim milk is 91% water. So, there are many options for rehydration.
Leigh Frame, George Washington University nutritionist and director of the Integrative Medicine program, told the Washington Post that eating a heavy meal is a bad idea. This is because it can be hard for the body to break down and because digestion itself creates heat.
Be careful not to drink too much plain water, as this can lower your body’s sodium to dangerous levels (called hyponatremia).
How much water do you need? According to The National Academies of Science, Engineering and Medicine, men should aim for 125 ounces (3.7 liters) and women for 91 ounces (2.7 liters). But about 20% of that fluid intake will come from foods. The amount you need to drink varies with your activity, body size, metabolism, and the environment. An easy guide is to aim to have your urine be a very pale yellow—if it is darker, that’s your clue to drink more.
Oral rehydration solution mixes are readily available in many countries. If these are not available and your budget is limited, you can make your own ORS. Some recipes are available from the University of Virginia, the Rehydration Project, among others.
Heat-related illness
Symptoms of illness from excessive heat run a spectrum. First can be heat cramps from dehydration and loss of electrolytes. Treat this with fluids like sports drinks with carbohydrates and electrolytes.
Sweating too little can contribute to your body overheating. Sweating too much, as can happen with many medications, can worsen dehydration,
Heat exhaustion can include nausea and vomiting, headache, dizziness, heavy sweating, fatigue and generally feeling unwell. You can cool the person with cool water or cold compresses and encourage cool liquids.
Further on the spectrum is heat stroke, which is more serious. The body can’t cool itself down, and the person’s temperature may rapidly rise. Symptoms include Confusion or altered mental status, and slurred speech, loss of consciousness, hot, dry skin or profuse sweating, and seizures.
Heat stroke is a medical emergency. While waiting for help, place cold wet cloths or ice on the head, neck, armpits, and groin; or soak the clothing with cool water. Also, circulate the air to speed cooling.
Tricks to help deal with the heat
Ideally, if you don’t have air conditioning, you want to get to a cooling center, library, shopping mall, or some place with air conditioning. Not everyone has that luxury.
Fans don’t work very well when the temperature gets into the 90s. Strip down and expose as much skin to the breeze as possible. Mist yourself with water to cool as it evaporates. Slowly blow the air over ice towards you for a small bit of relief.
Medications
Often overlooked with all of the problems people face now is the risk many medicines pose during the heat. Here are some of the risks:
Diuretics are very commonly used to treat hypertension and heart failure. They cause us to urinate more and can lead to dehydration. Common diuretics include hydrochlorthiazide (HCTZ), furosomide (Lasix), and acetazolamide (Diamox).
Other blood pressure medicines may lower your blood pressure enough to make you more likely to faint from the heat. These include:
—Angiotensin Converting Enzyme Inhibitors (ACE inhibitors) like Enalapril, Lisinopril, and Ramipril.
—Angiotensin II Receptor blockers (ARBs), as Valsartan and Losartan
—Calcium channel blockers, such as Amlodipine and Nifedipine
—beta blockers, such as Atenolol, Metoprolol, and Propranolol
Some antipsychotics, anticholinergics, and stimulants can interfere with your body’s ability to control its temperature.
A number of antidepressants affect sweating. Selective Serotonin Reuptake Inhibitors (SSRIs), like escitalopram (Lexapro), sertraline (Zoloft), fluoxetine (Prozac) and paroxetine (Paxil), can cause increased sweating. So can Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs), such as Duloxetine (Cymbalta) or Venlafaxine (Effexor). Both of these classes of antidepressants may contribute to dehydration.
Buproprion (Wellbutrin), which belongs to yet another class, and can also increase sweating.
In contrast, sweating is decreased with Tricyclic Antidepressants (TCAs), such as amitriptylene (Elavil), and typical and atypical antipsychotics. Haloperidol (Haldol), Olanzapine (Zyprexa), Quetiapine (Seroquel), Risperidone (Risperdal) are some medicines used to treat psychosis.
Anticholinergic agents include the antihistamines Benadryl, Dimetapp, Dramamine, and Unisom Sleep tablets. They are also sometimes used for incontinence and in COPD, Parkinson’s disease and asthma. They cause decreased sweating, which can contribute to overheating. The newer antihistamines, cetirizine (Zyrtec), fexofenadine (Allegra) and loratidine (Claritin), don’t have this effect.
Many other medications, including those for migraines and seizures, can cause increased sweating. See this CDC list for the most common ones.
Some of the risks are less likely to come to mind. For example, there can be drug toxicity when someone is dehydrated and is unable to adequately clear a medicine with a narrow therapeutic index—that is one where a small difference in the drug level can lead to serioius side effects. This can happen with apixaban (Eliquis) carbamazepine (Tegretol), and lithium).
Finally, if you get dehydrated enough to cause kidney injury, this might be worsened by even commonly used drugs like ibuprofen (Advil, Motrin) or other NSAIDs.
The Department of Health and Human Services says, “climate projections indicate that extreme heat events will become more frequent and intense in coming decades. Heat-related deaths have been increasing in the U.S., with approximately 1,602 occurring in 2021, 1,722 in 2022, and 2,302 in 2023.”
These are some of the reasons to try to prepare and take extra precautions during these heat spells.
