What’s Causing Your Lingering Cough and How to Treat It

Lingering coughs after upper respiratory infections like the common cold or flu are called post-infectious coughs. A lingering cough is mostly dry and are often referred to as "sub-acute," meaning it persists for more than three weeks after the infection, but less than eight.

Post-infectious coughs are a common type of lingering cough, affecting as many as one of every four people with an upper respiratory infection.

This article describes the types of infections that tend to cause lingering coughs, as well as how healthcare providers diagnose and treat a cough that won't go away. It also offers tips on how to reduce your risk of post-infectious coughs and upper respiratory infections in general.

Causes of Lingering Coughs

Lingering coughs often happen with uper respiratory tract infections. These types of infections occur anywhere within the nose, sinuses, throat (pharynx), or voicebox (larynx). Symptoms generally last seven to 14 days and may include fever, cough, sore throat, stuffy/runny nose, sneezing, headache, and muscle aches.

Lingering coughs are believed to be caused by either mucous draining into your throat (postnasal drip) or inflammation related to the initial infection.

The vast majority of upper respiratory infections are caused by viruses, and all of these can cause a lingering cough:

• Rhinovirus (common cold)
• Influenza (flu)
• Parainfluenza
• Adenovirus
• Respiratory syncytial virus (RSV)

Much less commonly, upper respiratory tract infections may be caused by bacteria like Haemophilus influenzae or Streptococcus pneumoniae. If these bacteria infect your sinuses, what's known as bacterial sinusitis, the infection can mimic that of a post-infectious cough until you're treated with an antibiotic.

There are also certain risk factors that increase the likelihood of post-infectious cough. These include having an upper respiratory infection that causes large amounts of mucus and/or the inability to adequately clear mucus from the lungs.

The risk of having a lingering cough also tends to increase the longer a person is ill with an upper respiratory infection.

Diagnosis

The diagnosis of post-infectious lingering cough is clinical, meaning it is based primarily on your symptoms and physical exam.

Your healthcare provider will ask you questions about when your cold symptoms started, what they were, the characteristics of your current cough, and whether you have any other symptoms.

They will also check your vitals (e.g., fever, heart rate, etc.) and perform a physical exam, during which they will look inside your nose and listen to your heart and lung sounds with a stethoscope.

A recent viral upper respiratory infection, a lack of fever, clear lungs, and cough that has not persisted past eight weeks are all signs a post-infectious cough.

Still, your healthcare provider may want to rule out other possible causes of your lingering cough, including:

• Gastroesophageal reflux disease (GERD)
• Asthma
• Pneumonia or bronchitis
• Bacterial sinusitis
• Whooping cough (Bordetella pertussis)
• Smoking
• Use of ACE inhibitors (drugs commonly used to treat high blood pressure)
• Congestive heart failure
• Lung cancer

Depending on their suspicion of any of these, various other tests may need to be performed before moving on to a treatment plan for a lingering cough that won't go away.

For example, your healthcare provider may order a chest X-ray. Findings should be normal with a diagnosis of post-infectious cough.

Tests like a computed tomography (CT) scan of your sinuses or chest or a pH monitoring test (measures the acidity level within your esophagus) may also be ordered.

When to Seek Medical Attention

A lingering cough on its own is not always a reason to worry. However, it's important to seek medical attention right away if you are experiencing a lingering cough and any of these symptoms:

• Coughing up significant amounts of mucous (wet cough)
• Wheezing or trouble breathing
• Persistent fever
• Unexplained weight loss
• Chest pain
• Coughing up blood
• Vomiting during or after coughing
• Unusual fatigue

Treatment

Even if it's not serious, having a lingering cough can be very annoying and disruptive. A post-infectious cough can significantly impact your quality of life. You may find it difficult to sleep or get your work done at home or at your job.

Once the diagnosis of post-infectious cough is made, your healthcare provider will ask you questions to determine whether your lingering cough is due to postnasal drip or inflammatory changes from the infection. Your treatment plan will be determined from there.

To avoid harmful side effects or medication interactions, be sure to check in with your healthcare provider about any treatments for a lingering cough you plan to try.

Medications for Postnasal Drip

A lingering cough related to postnasal drip is treated with an antihistamine like Dayhist (clemastine) or Chlor-Trimeton (chlorpheniramine).

While more sedating than newer drugs, these particular antihistamines are more effective at minimizing a post-viral cough.

If you are unable to tolerate the sedating effects of these medications, your healthcare provider may suggest a nasal spray like Astelin (azelastine), Flonase Allergy Relief (fluticasone propionate), or Atrovent nasal spray (ipratropium bromide) to help with a lingering cough.

The following antihistamines may also be tried:

• Allegra (fexofenadine hydrochloride)
• Claritin (loratadine)
• Zyrtec (cetirizine hydrochloride)

Medications for Inflammation

Some treatments for a lingering cough are a little more involved. A post-infectious cough related to inflammatory changes in airway tissue is treated similarly to asthma.

Your healthcare provider may perform a methacholine challenge test in which you breathe in a drug that narrows your airways. If it affects your ability to breathe well, you will be prescribed one or more of the following types of medications, depending on the severity of your symptoms:

• Inhaled corticosteroids
• Leukotriene receptor antagonist, like Singulair (montelukast)
• Oral prednisone

If the test does not show that you have sensitive airways, your healthcare provider may prescribe Atrovent HFA (inhaled ipratropium bromide).

Over-the-Counter Cough Medications

Even though there isn't much scientific evidence to back up their use, many people turn to over-the-counter medications to also help with a lingering cough that won't go away.

Cough suppressants like Delsym cough syrup are drugs that block the cough reflex. They usually contain the ingredient dextromethorphan.

Guaifenesin, another over-the-counter cough medicine, is found in Mucinex. In contrast to dextromethorphan, guaifenesin is a cough expectorant. It works by thinning the mucus in your airways so you can get rid of it more easily.

Cough drops, or throat lozenges, are also commonly used to manage a post-infectious cough, regardless of the underlying cause.

Cough drops often contain a combination of ingredients including honey, menthol, eucalyptus oil, and dextromethorphan.

Unfortunately, the benefit of these lozenges is questionable. In fact, experts suspect that cough drops maybe not be any better for managing your cough than sucking on a piece of hard candy.

There is also some concern that menthol, which cools and numbs your throat, may actually worsen a lingering cough.

Home Remedies

You can also try some non-medical treatments to ease a lingering cough. Certain home remedies are reasonable approaches to managing a post-infectious cough. Some people may even find them more soothing than other therapies.

Eucalyptus Oil

Eucalyptus oil is a colorless or pale yellow liquid that has a number of potential health benefits, including relieving post-infectious cough.

Eucalyptus oil is believed to calm cough by loosening a person's phlegm. You can use it by inhaling steam infused with eucalyptus oil (drop 12 drops of eucalyptus oil per 3/4 of boiling water). You can also apply an over-the-counter product that contains the oil, like Vicks VapoRub, to the skin on your chest.

Keep in mind that eucalyptus oil should not be used in children younger than age 2, or while a person is pregnant or breastfeeding.

It's also important to never ingest eucalyptus oil, as it's toxic if consumed by mouth.

Even when inhaled or applied to the skin, eucalyptus oil may interact with various medications, so be sure to tell your healthcare provider if you are using it.

Honey and Tea/Coffee

Drinking tea mixed with honey is a classic home remedy for treating a nagging cough. Experts suspect the medicinal effect of honey may be due to its antioxidant and antimicrobial properties.

For adults with a post-infectious cough, drinking coffee with honey in it has also been found to soothe a lingering cough.

In one study, nearly 100 adult participants with a subacute or chronic post-infectious cough were asked to drink a special solution containing either instant coffee/honey, steroids, or guaifenesin.

After drinking the solution every eight hours for one week, the frequency of the participants' coughs was measured.

Results revealed that the mixture of honey and coffee was significantly better at easing the participants' cough than the steroids or guaifenesin.

Experts suspect the caffeine from the coffee has anti-inflammatory properties and may help open up your airways so you can breathe more easily when you have a lingering cough.

Due to the risk of infant botulism—a potentially life-threatening condition caused by a bacteria-generated toxin—never give honey to a child younger than 12 months old. Also, you should avoid giving caffeinated tea or coffee to children.

Humidifier

By releasing moisture into the air, a humidifier may help clear mucus and ease a lingering cough. Some humidifiers may have a feature that allows you to add essential oils like eucalyptus or peppermint oil for extra cough relief.

For children, be sure to use a cool-mist humidifier. Warm-mist humidifiers or vaporizers can burn your child if they get too close to the steam.

Also, clean your humidifier daily, if possible, to prevent bacteria and mold from growing.

Gargle With Salt Water

Gargling salt water may help with a lingering cough by loosening and washing away phlegm in your throat.

To gargle salt water, add half of a teaspoon (tsp) of salt to a cup of warm water and mix until it is dissolved. Then, take a sip of the salt water, tilt your head back, gargle for around 10 seconds, and then spit it out.

If you're not sure if your young child can reliably spit the water out, you should avoid having them try this.

Prevention

If you want to avoid getting a lingering cough that won't go away, prevention is key. There are a few easy steps you can take to prevent developing an upper respiratory illness and a subsequent post-infectious cough.

These steps include:

• Wash your hands frequently with soap and water.
• Minimize close contact with people who are coughing or sneezing.
• Avoid touching your eyes, nose, and mouth. 
• Regularly disinfect common areas within your home and workplace.
• Stay up to date on your vaccinations (e.g., flu, pertussis, pneumonia, and COVID-19).

If you happen to get sick with an upper respiratory infection, resting your body is important. While it won't guarantee that you'll avoid a post-infectious cough, it will give your body a better chance for a quick and full recovery. Studies show that the risk of getting a lingering cough increases with the duration of the illness.

Another factor that may contribute to the risk of a post-infectious cough is the undertreatment of an upper respiratory infection. If there is a heavy build-up of mucus, you may be well served to get an expectorant like Mucinex to help clear the mucus rather than letting it sit in the lungs. Seek advice from a medical professional.

It's also sensible to try and avoid potential environmental irritants that may trigger or worsen a nagging cough, like dust or smoke.

Summary

A post-infectious cough is a lingering cough from an upper respiratory infection, like the common cold or flu, that persists for up to eight weeks after the infection has otherwise cleared.

The goal of treatment for a lingering cough is to ease symptoms while you recover. Cough suppressants, antihistamines, expectorants, or inhaled or oral steroids. Home remedies like humidifiers, eucalyptus aromatherapy, and gargling with salt water may also help.

Post-infectious cough can possibly be avoided by treating upper respiratory infections appropriately. This includes getting plenty of rest during the infection and using an expectorant to avoid the build-up of mucus in the lungs.