Lingering Cough After a Cold: Causes and Treatments - Verywell Health

Lingering coughs after a viral upper respiratory infection (URI), like the common cold or flu, are called post-infectious coughs. These coughs are mostly dry and come and go. They last more than three weeks after the infection but less than eight weeks without treatment, classifying them as "sub-acute."

Post-infectious coughs are common, affecting as many as one out of every four people with a URI.

This article reviews the infections that tend to cause lingering coughs, as well as how healthcare providers diagnose and treat your cough so you can finally feel better. You'll also learn how to possibly prevent a post-infectious cough.

Laura Porter / Verywell

Causes of Lingering Coughs

Upper respiratory tract infections refer to an infection of any area 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:

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 treated with an antibiotic.

Recap

Post-infectious coughs last less than eight weeks and are caused by a viral upper respiratory infection such as the common cold, the flu, or RSV.

Diagnosis

The diagnosis of post-infectious 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 history of a recent viral URI, lack of fever, clear lungs, and cough that has not persisted past eight weeks are all symptoms and signs pointing toward a diagnosis of a post-infectious cough.

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

Depending on their suspicion of any of these, various other tests may need to be performed before moving onto a treatment plan.

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

It's important to seek medical attention right away if you are experiencing a 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

Recap

A healthcare provider can usually diagnose a post-infectious cough based on symptoms and an exam, but may run other tests if they suspect another possible cause, such as asthma or GERD. Don't wait to seek an evaluation if you have symptoms such as persistent fever or chest pain.

Treatment

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 you plan to try.

Medications for Postnasal Drip

A 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).

The following antihistamines may also be tried:

Medications for Inflammation

A post-infectious cough related to inflammatory changes in airway tissue is treated similarly to asthma.

Your healthcare provider may administer 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:

If your testing 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 soothe their cough.

Cough suppressants like Delsym cough syrup are drugs that block your 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, also called 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 your cough.

Recap

Various medications can address different aspects of your cough, whether that's postnasal drip, inflammation, an overactive coughing reflex, or chest congestion. Which are best for you depends on why your cough is lingering.

Home Remedies

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 made from eucalyptus oil or by applying an over-the-counter product that contains it, like Vicks VapoRub, to the skin on your chest.

For inhalation, 12 drops of eucalyptus oil per 3/4 of boiling water is typically used.

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 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 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 instant 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.

Due to the risk of infant botulism, 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 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 reduce 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.

Recap

Home remedies may seem too simple to stand up to your lingering cough, but they can be helpful either alone or along with medication use. These include eucalyptus oil aromatherapy, tea and honey, coffee, using a humidifier, and gargling with salt water.

Prevention

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 developing a post-infectious cough, it will give your body a better chance for a quick and full recovery.

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

Summary

A post-infectious cough is a lingering cough from an upper respiratory infection, like the flu, that may last up to eight weeks without treatment. Diagnosis requires that other potential causes are ruled out first, like acid reflux and asthma.

Treatment may involve taking an antihistamine, using a steroid inhaler, and/or trying out various home remedies like inhaling steam containing eucalyptus oil. Prevention strategies, such as washing your hands frequently, are generally focused on not getting sick in the first place.

A Word From Verywell

While it's truly no fun to be "sniffly" and sick from the cold or flu, know that you are not alone. Viral URIs are very common, as is the irritating cough that sometimes lingers afterward.

That said, if your cough is particularly severe, is lasting eight or more weeks, or is not improving with home or OTC therapies, be sure to see your healthcare provider. You will also want to see your healthcare provider if you have worrisome symptoms along with your cough, like vomiting or weight loss.