A bad cough is almost always your body’s attempt to clear something irritating from your airways, whether that’s mucus from an infection, stomach acid creeping up your throat, or inflammation that makes your airways overly sensitive. The cause depends largely on how long you’ve been coughing. A cough lasting under three weeks is usually from a respiratory infection. One that persists between three and eight weeks is considered subacute, often a lingering effect of a recent illness. A cough that hangs on longer than eight weeks is classified as chronic, and the causes shift significantly.
How the Cough Reflex Works
Your airways are lined with sensory nerve endings that act like smoke detectors. When something irritates them, whether it’s a virus, a drop of mucus, or a particle of dust, they fire a signal up the vagus nerve to a “cough center” in your brainstem. That center then sends commands back down to your diaphragm, chest muscles, and vocal cords to produce the explosive burst of air you experience as a cough.
These nerve endings exist not just in your lungs and throat but also in unexpected places: your eardrums, sinuses, diaphragm, and even your stomach lining. That’s why acid reflux can trigger a cough, and why cleaning your ear with a cotton swab sometimes makes you cough. Different types of receptors respond to different triggers. Some react to physical touch and stretching, others to chemical irritants. When your airways are inflamed, these receptors become hypersensitive, firing at stimuli that wouldn’t normally bother them. This is a big part of why a “bad” cough feels so relentless.
Short-Term Cough From Infection
The most common reason for a sudden, severe cough is acute bronchitis, which is an infection of the lower airways that produces cough with or without phlegm for up to three weeks. The vast majority of these infections are viral. A cold, the flu, COVID-19, or RSV can all inflame the lining of your bronchial tubes, triggering heavy mucus production and a persistent cough as your body tries to clear it.
Bacterial infections cause acute cough less often, but they tend to produce thicker, discolored mucus and sometimes a fever that doesn’t improve after several days. Pneumonia is the more serious bacterial possibility, and it typically comes with shortness of breath, chest pain, and fatigue on top of the cough.
The Post-Infection Cough That Won’t Quit
If you’ve already recovered from a cold or respiratory infection but your cough keeps dragging on, you’re dealing with a post-infectious cough. This is extremely common and typically lasts three to eight weeks after the original illness has cleared. The infection itself is gone, but the inflammatory cascade it triggered leaves your bronchial tubes swollen and hypersensitive. Mucus production stays elevated while your airways’ ability to clear that mucus is temporarily reduced. The combination keeps you coughing long after the virus has left your system.
This type of cough can feel alarming because it lingers so long, but it generally resolves on its own. The key distinction is that you’re otherwise feeling better: no fever, no worsening symptoms, just a stubborn cough.
Three Common Causes of Chronic Cough
When a cough persists beyond eight weeks, three conditions account for the majority of cases.
Acid Reflux
Gastroesophageal reflux disease doesn’t always announce itself with heartburn. Stomach acid can travel up the esophagus and reach the throat, irritating the larynx and triggering a chronic dry cough. It can also cause tiny amounts of acid to be inhaled into the airways (microaspiration), or it can stimulate a nerve reflex between the esophagus and the lungs that produces coughing without any acid actually reaching the throat. Treating reflux improves cough and related symptoms in roughly 70% of patients. If your cough is worse after meals or when lying down, reflux is a strong possibility.
Asthma
Not all asthma involves wheezing. Cough-variant asthma produces a dry, persistent cough as its primary symptom, often worse at night, during exercise, or after exposure to cold air or allergens. The airways narrow and become inflamed, and the constant irritation keeps the cough reflex firing.
Upper Airway Cough Syndrome
Previously called post-nasal drip, this occurs when excess mucus from your sinuses drains down the back of your throat and irritates the cough receptors there. Allergies, chronic sinusitis, and even weather changes can trigger it. The cough tends to worsen at night because lying flat allows mucus to pool in the back of the throat rather than draining forward. Elevating your head six to eight inches above your body at bedtime can reduce both post-nasal drip and reflux-related coughing.
These three conditions frequently overlap. Reflux can worsen asthma, and sinus drainage can irritate airways already sensitized by either condition. If you have a chronic cough, more than one of these may be contributing.
Medications That Cause Cough
A class of blood pressure medications called ACE inhibitors is one of the most overlooked causes of a persistent dry cough. Somewhere between 4% and 35% of people taking these drugs develop a cough, and it’s a common enough problem that nearly one in five patients stops taking them because of it. The cough is typically dry with a tickling or scratching sensation in the throat. It happens because the medication causes certain irritant compounds to build up in the airways rather than being broken down normally. If you started a new blood pressure medication in the weeks or months before your cough appeared, this is worth discussing with your doctor. Switching to a different type of blood pressure drug usually resolves the cough completely.
Why Your Cough Gets Worse at Night
If your cough ramps up the moment you lie down, gravity is working against you in two ways. First, mucus from your sinuses that drained harmlessly during the day now slides down the back of your throat. Second, stomach acid that stayed in your stomach while you were upright can flow toward your esophagus and throat. Both of these irritate the same cough receptors. Sleeping with your upper body elevated, rather than just adding a pillow under your head, can make a meaningful difference. Asthma also tends to flare at night due to natural changes in airway tone and hormone levels during sleep.
When a Cough Signals Something Serious
Most coughs, even bad ones, are not dangerous. But certain symptoms alongside a cough need prompt attention: coughing up blood, unexplained weight loss, persistent fever that isn’t improving, shortness of breath or difficulty breathing, and chest pain. A cough lasting longer than eight weeks without an obvious explanation also warrants evaluation, typically starting with imaging of the chest. Any cough that’s getting progressively worse rather than better deserves medical attention regardless of how long it’s been present.
What Actually Helps a Bad Cough
Over-the-counter cough suppressants have a surprisingly weak track record. The most common active ingredient in cough syrups, dextromethorphan, performs about on par with honey in studies of cough relief. In children, honey has actually outperformed the antihistamine-based cough suppressants across most measures of nighttime cough severity, including cough intensity, frequency, and how much the cough disrupts sleep. Honey’s benefit appears strongest in the first three days of a cough. After that, most remedies converge toward similar modest effects. (Honey should never be given to children under one year old due to botulism risk.)
For a post-infectious cough, time is the most effective treatment. Staying hydrated, using a humidifier, and avoiding irritants like smoke can keep your healing airways from being further provoked. For chronic cough, the most effective approach is identifying and treating the underlying cause, whether that’s managing reflux, controlling asthma with an inhaler, or treating sinus issues. Suppressing the cough without addressing the trigger rarely works long-term.