by Erin Jones | CBS11

DALLAS (CBSDFW.COM) – The heat can take a toll on your health, but some don’t realize the medications they’re taking may be making them more susceptible to heat-related illnesses.

“In these times of extreme heat you always have have to be careful of what you’re taking,” Emergency Medical Physician Dr. Van Ton with Methodist Charlton Medical Center said.

Antihistamines can decrease the body’s ability to stay hydrated and respond to heat.

Waiting to see Niall Horan and Maren Morris perform in Fair Park Friday night, Rhonda Staudt was sweating and suffering from allergies.

“They’re horrible,” she said. “You don’t get a good breath, but if you wan’t to go to something like this you just have to do it anyway.”

On top of other allergy remedies, she takes an over the counter antihistamine. She said she was not aware of the effect they can have in the heat.

“A lot of them are surprised and they don’t take into consideration that their medications, especially over the counter medication, can cause such traumatic responses,” Dr. Ton said.

On top of antihistamines, doctors say also look out for beta blockers and stimulants for ADHD which make it harder for the body to release heat and diuretics which rids the body of water.

“If they can avoid being outside during the heat if at all possible it’s the most important thing,” Dr. Ton said. “Stay hydrated.”

During the summer months, Dr. Ton said his emergency room normally sees around 200 patients a day, but in recent days they’ve seen about 250 patients a day. A good portion of the extra patients were suffering from heat related illnesses.