Colds come with a slew of symptoms, including runny or stuffy nose, sneezing, coughing, sore throat, headache, body aches and even mild fever. To alleviate them, we often turn to cold medications — concoctions of various active ingredients that are designed to treat all the symptoms all at once.

But certain drugs used to relieve cold symptoms can also affect the cardiovascular system, and in ways that can be especially problematic for people with underlying heart issues.

"We tend to assume that over-the-counter medications are safe no matter what," says Dr. Sadeer Al-Kindi, a preventive cardiologist at Houston Methodist. "It's important to realize that medications can sometimes be harmful for certain people or in certain situations."

When it comes to treating cold symptoms, decongestants, in particular, pose a threat to the heart that certain people should think twice about.

How decongestants affect the heart

"A stuffy, congested nose is referred to as rhinitis, which is inflammation within the inner membrane of the nose," says Dr. Al-Kindi.

This inflammation is a natural part of your body dealing with a cold. To get immune cells to the site of the infection, blood flow to the nose increases. As these immune cells create substances that help fight off the virus, fluid build-up occurs. This increased pressure and swelling causes nasal congestion.

That's where decongestants come in. Pseudoephedrine and phenylephrine are probably the most well-known examples.

"The way these decongestants work is by constricting the small blood vessels in the nose," explains Dr. Al-Kindi. "By making vessels smaller, blood flow is reduced and the inflammation causing the congestion clears up."

The catch, however, is that these medications don't just affect blood vessels in the nose. Oral decongestants, in particular, work systemically and tighten blood vessels throughout the entire body.

"Whenever the resistance of blood flow is increased — by taking a medication that constricts blood vessels, in this case — the heart is forced to work harder," explains Dr. Al-Kindi. "It has to struggle a bit more to push blood throughout the body."

That's why decongestants can have more sweeping effects beyond relieving congestion. They can increase blood pressure and affect the heart's rhythm.

And by the way, some might not even work so well. An FDA advisory panel just stated that oral phenylephrine, which is used in many cold medicines today, is ineffective as a nasal decongestant.

Decongestants may have harmful effects in susceptible people with preexisting heart issues

For a heart that's healthy, dealing with temporary tightening of blood vessels throughout the body is a manageable occurrence as long as oral decongestants are taken as directed — at the recommended dosage and for no more than seven days. (This timeline shortens to just a few days if you're taking a nasal decongestant.)

So who shouldn't take decongestants?

"The caution is for people who have a health issue that affects how well the heart and vascular system are functioning," warns Dr. Al-Kindi.

Taking decongestants is riskiest for people with:

• Uncontrolled high blood pressure (hypertension)
• A predisposition for developing an arrhythmia (irregular heartbeat)
• Heart failure
• Prinzemetal angina (spasm of the coronary artery), also called variant angina

These heart conditions are characterized by underlying problems with blood pressure, maintaining a normal heartbeat or the ability to pump blood. Taking a decongestant can exacerbate these issues, potentially increasing the risk of heart attack, stroke and other life-threatening cardiovascular events.

Pseudoephedrine is the most well-documented example of how decongestants have been shown to negatively impact the heart. But doctors anticipate similar side effects and complications in newer decongestants that aren't widely studied yet — such as phenylephrine and oxymetazoline — because the class of medications works by a similar mechanism.

It's why stand-alone decongestants and multi-symptom cold medications containing a decongestant have warnings on the label for people with high blood pressure and heart disease.

Oral decongestants can also interact with certain blood pressure medications — making these drugs either more or less potent. Since there are many different types of blood pressure medications, and some people take more than one type to treat their high blood pressure, this is a tricky situation for you to navigate yourself at home.

"It's always good practice to consult your doctor before taking a new over-the-counter medication," recommends Dr. Al-Kindi. "Your doctor knows what you're already taking and can check for potential drug interactions."

Ways to relieve congestion that don't stress the heart

If you're more vulnerable to the side effects of decongestants, Dr. Al-Kindi offers alternative ways to relieve congestion without putting your heart at risk.

"People with heart issues will need to be a bit more conservative," says Dr. Al-Kindi. "Fortunately, home remedies are usually enough to help relieve congestion, especially when it's a mild cold that you know is going to get better on its own in time."

Better alternatives to help ease congestion include:

• Using a nasal saline spray
• Humidifying the air, by taking a hot shower, for instance
• Taking an antihistamine instead, which helps relieve nasal inflammation in a different (albeit slower) way

And one last warning: It's not always obvious when an over-the-counter medication contains a decongestant. This is especially true for multi-symptom options that combine many different medications into a single dose. Always read the label before taking any medication, making note of the active ingredients, dosage guidelines and any warnings that may apply to you.

The active ingredient names of common decongestants to be on the lookout for include pseudoephedrine, phenylephrine and oxymetazoline.