For the past several days, parts of Missouri have been under an extreme heat warning with high temperatures and heat indexes well above 100 degrees.
Even though that current advisory will end tonight, doctors warn there are still many people with chronic conditions or who take certain medications that are at a higher risk of heat-related illness.
In 2025, there were 35 deaths in Missouri with heat-related causes according to the Missouri Department of Health & Senior Services.
And according to the Mayo clinic, people more susceptible to heat should start taking precautions when the heat index rises above 91 degrees.
The most important thing that a person can do, Sampson said, is prepare for the heat — wear appropriate clothing, plan outdoor activities during the coolest parts of the day and be intentional about hydration.
This includes people 65+, young children, pregnant people, those with chronic conditions and individuals on certain medications.
Dr. Christopher Sampson, an emergency medicine doctor at MU Health Care, said many common medications can reduce a person’s ability to handle heat — either by increasing the frequency of urination or a person’s ability to sweat.
“Some of the medications to watch out for are a lot of the blood pressure medications,” Sampson said. “The way they work is they help you pee off fluid to kind of lower your blood pressure, so by doing that, you can get dehydrated much more easily, especially if it's hot out and you're already sweating.”
He added that many psychiatric medications used to treat depression, schizophrenia or bipolar disorder can impact a person’s ability to sweat, which is one of the major ways humans regulate temperature.
Sampson said people should also be aware that some over-the-counter allergy medications — most commonly diphenhydramine, or Benadryl – can also impact how a person reacts to heat and make them more dehydrated.
“Some people just think that's only in an allergy pill, but diphenhydramine can be found also in a lot of other medicines,” Sampson said. “Sometimes it's in some of the sleep aids that you might see, or some of the cold and flu medications.”
Sampson said there’s also many folks with chronic health conditions that should be more careful when it’s hot outside, such as those with high blood pressure, lung conditions, heart disease or pregnancy.
“All of those, your symptoms can be worsened, or you can feel more fatigue, or even be more at risk for serious medical emergencies when it's super hot out,” Sampson said.
He stressed that awareness of the heat outside is especially important for those diabetes, as they tend to be on some of the medications that impact the body’s response to heat and the condition itself leads to dehydration.
“When your blood sugar gets elevated, it does make you urinate more frequently, so they also can be at risk of becoming dehydrated quicker, “ Sampson said.
The most important thing that a person can do, Sampson said, is prepare for the heat — wear appropriate clothing, plan outdoor activities during the coolest parts of the day and be intentional about hydration.
He says if a person becomes excessively thirsty or feels a bit dizzy, to remove them from the heat and go to a cool environment.
But if someone becomes confused, has hot, dry skin, loses consciousness or begins to have seizures, call 911 immediately — as these are signs of heat stroke, a serious heat-related illness that can lead to death.
“Those are true medical emergencies, and those are the people that really need to be rapidly cooled down.”
Sampson added that if someone is uncertain about the impact of their medications or chronic conditions on their ability to regulate heat, reach out to your doctor or a pharmacist.
