An American summer wouldn’t be complete without warm weather.

When the heat gets extreme, however, it can affect our health for a variety of reasons.

Dr. Mona Sarfaty, director of the climate and health program at George Mason University’s Center for Climate Change Communication, said that when temperatures are above normal over the span of a few days that can stress our bodies.

The heat can affect infants and older adults as well as people who work outside, do physical activity, don’t have access to air conditioning, or have a health condition aggravated by the heat.

“You can start to feel lightheaded, dizzy, faint … you can just feel unusually fatigued and not realize what’s happening,” Sarfaty told Healthline.

Read more: Tips for beating summer heat »

Effects on older adults

Older adults, for example, have diminished thirst and may not stay hydrated.

Older adults also don’t sweat as much as younger people, and this may make them more vulnerable to heat-related conditions such as heat stroke, heat exhaustion, and heat cramps.

Caretakers need to be aware of this, Sarfaty said, especially if the person is less mobile and does not have access to air conditioning.

Many areas have cooling stations for those who need to be in air conditioning on a hot day.

Read more: Everything you wanted to know about sunscreen »

Heat and health conditions

Other symptoms of heat-related illness include headaches and rapid heartbeat.

Certain populations of people with existing health conditions can be prone to heat-related illnesses.

Those with chronic obstructive pulmonary disease (COPD), allergies, and asthma are more susceptible when temperatures are higher.

Sarfaty has surveyed doctors treating lung conditions who say heat exacerbates those conditions.

Sarfaty has also found that ragweed, a common allergen found throughout much of the country, is producing more potent pollen for longer durations throughout the year.

This is due to an increase in atmospheric carbon dioxide, which causes temperatures to rise.

Kidney stones may also become worse when the temperatures rise. People tend to get dehydrated in the heat, which can make dealing with this painful condition more difficult.

Most people too should drink two to four more cups of liquid than normal during a heat wave, Sarfaty said.

Incessantly hot days also make it harder on those with heart disease and cystic fibrosis.

Read more: What are we breathing and how bad is air pollution for us »

Be cautious with medication

Certain medications, such as antihistamines, tricyclic antidepressants, benzodiazepines, beta-blockers, diuretics, and laxatives are just a few drugs that may make someone more vulnerable to feeling ill when a heat wave kicks in.

“People may not identify a period of increased warm weather as problematic,” Sarfaty said.

But it certainly can be.

Anyone experiencing symptoms should move into a cooler setting and drink plenty of liquids. In many cases, the illness will subside.

“When it progresses from heat exhaustion to heat stroke, someone can faint or go into a coma,” Sarfaty noted.

Between 1999 and 2010, there were 7,415 deaths due to heat-related causes — an average of 618 per year, the Centers for Disease Control and Prevention (CDC) reports.

Read more: Doctors urged to take action on climate change »

Heat and climate change

Expect to see more heat-related illnesses as the global temperature warms up, Sarfaty said.

“Climate change has everything to do with people’s health,” she said.

When we hear about penguins and polar bears in the Arctic affected by warmer weather, it doesn’t really hit home.

But warm weather makes it a real issue for everyone because no one is comfortable in extreme heat, she said.

“There are all of these health implications that really have everything to do with all of us,” Sarfaty added.