As respiratory illnesses surge this winter, there’s one symptom many patients hope will just go away: the dreaded cough.

“At this time of year, many people suffer from minor coughs due to common colds, allergies or sinus irritation with post-nasal drip,” Dr. Whitney Hardy, family medicine physician at Ochsner Health in New Orleans, Louisiana, told Fox News Digital.

One of the most common causes of a nagging cough is known as post-nasal drip, which occurs when the insides of the nasal passages become congested.

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Often, this stems from a viral infection or an allergy trigger, according to the American Lung Association’s website.

Eventually, the nasal discharge drips to the back of the throat, causing the body to cough reflexively.

In some cases, coughs can be very debilitating, but in other cases they can resolve on their own without affecting daily activities — so it’s not always easy to know when to seek medical attention.

Here’s what the experts say you should know.

Why do we cough?

“A cough is a natural reflex in response to things like excess moisture in the lungs, foreign objects and mucus-producing infections,” Hardy told Fox News Digital.

After the irritant tickles the throat or airways, it sends a message to the brain that there is something in the body that shouldn’t be there, according to Mayo Clinic’s website.

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The brain then sends a message to the chest muscles to cough in order to get the irritant out of the body.

It’s natural for people to cough from time to time — but if the symptom becomes severe or persists for too long, it can irritate the lung and induce even more coughing.

Too much coughing can lead to trouble sleeping, dizziness, headaches, vomiting, fainting, chest pain and even broken ribs, Mayo Clinic noted.

“This mechanism is important when we have an active infection and need to remove pus or fluid that will create further damage in the lung if it persists,” Dr. Baljinder S. Sidhu, a pulmonologist and sleep specialist who is the partner of Pacific Coast Critical Care Group in Southern California, told Fox News Digital.

“Lingering cough is often caused by irritated lung mucosa with minimal triggers.”

What are the different types of coughs?

A cough that lasts less than three weeks is known as an acute cough, per Mayo Clinic.

“An acute cough typically occurs with a viral or bacterial infection, such as the flu or pneumonia,” Hardy said.

“Sometimes, this type of cough can last up to three weeks, even after infection symptoms clear,” she added.

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“Acute coughs are dry and get worse during the day, but almost completely stop at night.”

Lung irritants such as smoke, dust and chemicals are also common causes of an acute cough.

A subacute cough lasts between three and eight weeks, and often occurs after a lingering respiratory infection, experts say.

A cough lasting for more than eight weeks is known as a chronic cough, according to the American Lung Association.

Asthma, gastroesophageal reflux disease (GERD) and a blood pressure medication known as lisinopril can all lead to a chronic cough.

Some life-threatening conditions, such as lung cancer and heart failure (where fluid from the heart backs up into the lung), may also cause a chronic cough, experts warned.

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“Most coughs associated with a recent cold or viral illness will resolve on their own without additional treatment,” Liz Husted, M.D., a family medicine physician at Mayo Clinic Health System in La Crosse, Wisconsin, told Fox News Digital.

“A cough after a viral illness can commonly last up to six weeks; typically, no additional treatment is needed.”

When does a cough become worrisome?

“A cough is always a concern when accompanied by shortness of breath or chest pain,” Husted said.

“This is to be evaluated by a physician right away.”

Always see a doctor if your cough lasts for more than eight weeks, as it may be necessary to get a chest X-ray to help diagnose the cause, the American Lung Association states on its website.

Regardless of how long your cough lasts, experts recommend seeing a doctor if you experience severe cough, fever, difficulty breathing or wheezing.

Phlegm with pus (thick green discharge) or blood, chills, night sweats and weight loss are other red flags that indicate the need for medical attention.

Should you use home remedies?

Over-the-counter (OTC) cough medicines are safe for adults to take for acute coughs, as long as the cough is not associated with any worrisome symptoms, according to experts. (Check with your doctor to be sure.)

“These over-the-counter medications are usually a combination of several medications, including dextromethorphan, guaifenesin, phenylephrine and/or Tylenol,” Sidhu said.

Dextromethorphan is a cough suppressant that acts directly on cough receptors, the doctor noted.

Guaifenesin works by making mucus thinner and easier to bring up so that less irritant is left behind.

“Phenylephrine is a decongestant that helps treat nasal congestion and postnasal drip,” Sidhu said.

Parents or caregivers should check with their pediatrician first before administering cough medications to children, experts advise.

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Also, OTC medications only treat the symptoms — not the underlying cause.

Past research has shown that they are no more effective than placebo medications in treating coughs.

“To help with an ongoing cough, use of a humidifier is recommended to keep plenty of moisture in your immediate atmosphere,” Hardy added.

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