Why Am I Coughing Up Brown Mucus?

Are you coughing up brown mucus? It might look alarming, but the color alone doesn’t tell the whole story. From dry air to infections (and everything in between), figuring out what’s behind that murky mucus is key to clearing it up for good.

Coughing up brown mucus is, well, not the kind of surprise anyone wants first thing in the morning. It’s a bit gross, a little worrying, and practically guaranteed to make you wonder: what the heck is going on in there? Don’t worry; many of us have hacked up a suspicious loogie at some point (mine came courtesy of a nosebleed—delightful).

Sometimes the culprit behind that brown gunk is simple: dried blood or leftover gunk from a cold. Other times, it can hint at something more serious, especially if you smoke or are around a lot of dust or pollution.

So, if you’re wondering, why is my mucus brown? You’re in the right place. Here’s what to know about when it’s common vs. concerning, the top causes, quick at-home fixes, and when it’s time to check in with a clinician.

Why is my mucus brown? (color 101)

If your usual clear snot suddenly looks like it spent the night rolling around in dirt, or you hacked up a bit of brown goo, something’s up.

Mucus is your body’s built-in defense system—a slippery, germ-trapping, airway-moisturizing fluid that keeps your respiratory tract healthy. Normally, it’s clear, thin, and barely noticeable. So when it turns brown, thick, or sticky, that’s your body waving a little flag that something’s changed.

The brown tint often comes from old blood—which can show up with infections, inflammation, or certain lung conditions—but it’s not always that serious. Sometimes, it’s just dust, smoke, or other particles you’ve inhaled coloring the mucus on its way out.

Brown mucus can come from your sinuses (upper airway) or lungs (lower airway), and pinpointing where it’s coming from helps determine what’s really going on and how to treat it (more on this in a bit).

Common causes of brown phlegm

Before you spiral on WebMD, take a breath—there are plenty of everyday reasons your phlegm might look a little brown and sketchy. Here are some of the most common culprits (and a few rarer ones).

Common causes of brown mucus

Irritants and environment

What you breathe matters. If you’re hacking up brown phlegm, your environment could be the culprit. Smoke, smog, or industrial dust can all leave their mark—literally.

• Smoking is one of the biggest offenders. Tar from tobacco smoke builds up in your lungs and mixes with mucus, turning it brown or even black. Smoking also thickens mucus and paralyzes your cilia (the tiny hair-like cells that sweep out gunk from your lungs), so the junk just sits there.
• Air pollution can do similar damage. Inhaling particles like dust, dirt, or pollutants can trap irritants in your airways, triggering inflammation and tainting your mucus with a brown tint. People who work in dusty jobs—think construction or mining—are especially at risk. In fact, conditions like coal workers’ pneumoconiosis (aka “black lung”)—a chronic lung disease due to repeated inhalation of mineral dust—are extreme examples of what long-term exposure can do.

Upper airway issues

Sometimes the rust-colored phlegm isn’t coming from deep in your lungs at all: brown mucus from the nose or sinuses can trickle down.

• Sinus infections (acute or chronic) inflame and swell your sinus lining, which can cause “minor surface bleeding,” says Geoffrey B. Trenkle, DO, a board-certified surgeon in otolaryngology and facial plastic surgery and CEO and founder of the Los Angeles Center for Ear, Nose, Throat and Allergy. That dried blood mixes with mucus, giving it a brown or rusty hue. With chronic sinusitis, a crust might form too, commonly adding to the brown discoloration, Dr. Trenkle explains. During sinus infections, the “buildup of thick mucus and debris” can also change the color of your phlegm, adds Elizabeth Lumpkin, MD, an anesthesiologist and clinical advisor at Southeast Addiction Tennessee.
• Postnasal drip happens when mucus from your nasal cavity and sinuses drains down your throat, says Dr. Trenkle. If that mucus picks up old blood or pollutants along the way, it can look brownish by the time you spit it out, explains Dr. Lumpkin.

Lower respiratory infections

If the brown mucus from your throat is coming from deep in your chest, you might be dealing with an infection lower down.

• Bronchitis inflames the bronchial tubes and often causes a cough with mucus. It can also bring on shortness of breath, wheezing, and chest tightness. Viruses (like the ones that cause colds and the flu) are the usual suspects, but smoke, fumes, or bacteria can trigger bronchitis, too.
• Pneumonia is a nasty infection that fills your lung’s air sacs with pus and fluid, producing thick green, yellow, or bloody mucus. Other signs include fever, chills, chest pain, and exhaustion.

Old blood from airway irritation

Hard, repetitive coughing can rupture tiny blood vessels in your airways, leaving behind small amounts of dried blood that tint your mucus brown. The same goes for minor nasal injuries like from dry air or aggressive nose-picking (kids are pros at this one). That dried blood can drip down and show up in your phlegm later.

Chronic lung conditions

If brown phlegm sticks around for weeks or months, it could point to an underlying chronic condition.

• Cystic fibrosis: causes thick, sticky mucus to clog the lungs and other organs.
• Bronchiectasis: permanently widens parts of the airways, trapping mucus that turns yellow, green, or brown.
• Chronic obstructive pulmonary disease (COPD): damages airways or other parts of the lung over time, causing inflammation, breathing problems, chronic cough, and mucus buildup.

In chronic lung conditions, the brown tint often comes from old blood and ongoing inflammation. Sometimes bacteria settle in and slowly change the look and feel of your phlegm over time.

Less common causes

Brown phlegm, in rare cases, can signal a condition that does not just self-resolve but needs to be actively address. These can include:

• Fungal infections like Aspergillosis can cause brown or bloody mucus, especially in people with lung disease or weakened immune systems. Symptoms include wheezing and shortness of breath.
• Tuberculosis (TB) is another potential cause. It’s a bacterial infection that often affects the lungs and causes persistent coughing (sometimes with blood), fever, weight loss, and night sweats.
• Pulmonary embolism—when a blood clot, often from the legs, travels to the lungs—can also lead to coughing up brown or bloody mucus. Other red flags include sudden shortness of breath, chest pain, rapid heartbeat, or fainting. This one’s a medical emergency—get help fast.

Brown mucus from nose vs throat (clues)

Where brown mucus comes from can reveal a lot about what’s going on in your body. Whether it’s dripping down from your sinuses or bubbling up from your lungs, the source determines both the cause and the cure. Here’s how to tell the difference, according to Drs. Trenkle and Lumpkin.

When it’s coming from the nose or sinuses: If you’ve blown through a box of tissues (literally) in record time, you’re probably dealing with mucus from your upper airway, aka your nose or sinuses. You’ll notice it when you’re blowing, sniffing, or constantly clearing your throat from postnasal drip. Other telltale signs: nasal congestion, sinus pressure or pain (around your eyes, cheeks, or forehead), headaches, sneezing, or a dulled sense of smell. Basically, if your face feels full and your head feels heavy, the problem’s probably upstairs.

When it’s coming from the lungs: Mucus that starts lower down— in your lungs or chest —has a totally different vibe. It tends to come out after a deep, forceful cough (you know, the kind that shakes your whole ribcage). It’s often paired with shortness of breath, wheezing, or chest tightness. Some people even feel a rattling sensation when they breathe. If that sounds familiar, your brown mucus is more likely tied to a lower respiratory issue like bronchitis, pneumonia, or COPD.

Still not sure where it’s coming from? An ENT (ear, nose, and throat) specialist can get to the bottom of it with a nasal endoscopy, says Dr. Trenkle. This quick, in-office procedure uses a tiny camera to peek inside your nasal and sinus passages, spotting any bleeding, crusting, or inflammation that could explain your symptoms.

Associated symptoms that matter

Brown mucus rarely flies solo—it usually tags along with other symptoms that can help clue you in to what’s going on.

If a sinus infection is to blame, Dr. Trenkle says you might notice:

• Postnasal drip (that annoying drip down the back of your throat)
• Pain or pressure in your upper teeth or face
• Nasal congestion or blockage
• A weaker sense of smell
• Sore throat or constant throat clearing from all that mucus trickling down

Depending on the culprit, other symptoms may join the party, too. Think fatigue, chest discomfort, fever, headaches, shortness of breath, or a lingering cough, adds Dr. Lumpkin.

When to worry (a.k.a. red flags you shouldn’t ignore)

Red flags for respiratory symptoms:

• Coughing up or blowing out lots of bright red blood or blood clots
• Persistent nosebleeds that won’t stop
• New or severe shortness of breath
• Chest pain
• Rapid breathing
• High fever
• Night sweats
• Confusion
• Difficulty waking up
• Weight loss
• Lump in neck

Most of the time, brown mucus is gross but harmless. But sometimes, it’s your body sounding an alarm.

“While most brown mucus is benign and related to minor nasal irritation, there are specific red flags that warrant immediate medical attention,” says Dr. Trenkle.

Red flags for respiratory symptoms

Call your provider or book an appointment with General Medicine ASAP if you notice any of these warning signs, according to Drs. Trenkle and Lumpkin:

• Lots of blood: You’re coughing up or blowing out a large amount of bright red blood or blood clots, or can’t get a nosebleed to stop.
• Trouble breathing: New or severe shortness of breath, chest pain, or rapid breathing.
• Signs of systemic illness: High fever, night sweats, confusion, or difficulty waking up.
• Symptoms that won’t quit: Brown mucus lasting several weeks with no clear cause, especially if you’re also losing weight or notice a persistent lump in your neck.

Bottom line: if your brown mucus is paired with bleeding, breathing issues, or other serious symptoms, it’s time to stop Googling and start dialing your doctor.

At-home care (short-term relief for mild cases)

Most of the time, brown mucus is your body’s way of flushing out germs, dead immune cells, and other unwanted guests. The good news: a few simple home remedies can make things a whole lot more manageable whether it’s a short-lived cold or a chronic culprit behind your congestion.

Here’s how to get quick relief:

• Hydrate like it’s your job. Water helps thin mucus so it’s less thick, sticky, and gross. The more you drink, the easier it is for your body to move that gunk along.
• Rinse and repeat. A nasal rinse can help flush out mucus from your nose and sinuses. Just make sure you’re using distilled or boiled (then cooled) water to keep things clean and safe.
• Use a warm compress. A little warmth over the nose and forehead may help relieve sinus pressure. Plus, it feels super comforting.
• Use the right over-the-counter helpers:
  • Expectorants thin out mucus so you can actually cough it up.
  • Decongestants shrink swollen nasal passages for temporary relief. However these medications can raise your blood pressure and contribute to urinary retention, so use caution.
  • Antihistamines calm the allergic reactions that send mucus production into overdrive.
  • Aspirin or acetaminophen can help with fever or discomfort, but never give aspirin to anyone under 18.
• Add some humidity. Running a humidifier keeps the air moist, which helps loosen phlegm and makes coughing it up less of a chore. No humidifier? No prob. Just breathe in some steam from a hot shower.
• Move your body. A quick walk or light activity can actually help your lungs clear out extra mucus.
• Elevate your head at night. When you lie flat, mucus pools in your throat (eww). Sleeping with an extra pillow helps it drain instead.
• Avoid irritants. Smoke, pollution, and harsh fumes can all make mucus worse, so steer clear when you can. And if you smoke, now’s your cue to quit.

While these remedies can make you way more comfortable (and sometimes that’s all you need to ride out a mild case), they only treat the symptoms, not the root cause. If the gunk keeps coming or your symptoms stick around, it’s time to check in with your healthcare provider.

Diagnosis: what a clinician might do

When it comes to brown mucus, your provider turns into a bit of a detective. To figure out what’s behind the discoloration, they’ll start by asking about your symptoms—when they began, how severe they are, and what makes them better or worse. They’ll also dig into your medical and family history for any red flags or patterns. From there, expect a physical exam, where your clinician will listen to your lungs with a stethoscope to check for wheezing, crackling, or other unusual sounds.

If your symptoms point to something deeper, they may order tests to get a clearer picture.These help pinpoint whether you’re dealing with an infection, inflammation, or something more serious. Common tests include:

• Sputum culture: Analyzes the mucus you cough up to check for bacteria, fungi, or other pathogens.
• Chest x-ray: Captures images of your lungs and chest structures to spot infection, fluid buildup, or damage.
• Blood tests: Detect signs of infection or inflammation, and determine if an infection has spread to the bloodstream.
• Pulse oximetry: Measures how much oxygen is in your blood (low levels can signal trouble breathing).
• Chest CT scan (computed tomography): Uses x-rays and computer technology to produce detailed images of your lungs and airways, helping identify structural issues or hidden infections.
• Bronchoscopy: A procedure that lets doctors look directly inside your airways using a flexible tube. It can also collect tissue or fluid samples for further testing.

Diagnosing brown mucus isn’t a guessing game—it’s a process of elimination. These tests help your provider move from “maybe” to “definitely,” so you can get the right treatment faster.

Treatment options (by cause)

The cause behind your brown gunk makes all the difference because treatment isn’t one-size-fits-all. Here’s how your next steps might look, depending on what’s really going on.

Irritant-related

If brown mucus is your body’s way of saying, “Enough with the irritants!”, listen up. The first step is simple but crucial: avoid whatever’s causing the irritation whether that’s dust, smoke, or chemical fumes. Again, if you smoke, this is your sign to kick those cigarettes to the curb (your sinuses and lungs will thank you).

Saline nasal rinses are a go-to for clearing out the junk. They wash away dust, pollen, and thick mucus while soothing irritation from allergies, colds, or sinus infections.

In more serious cases—like black lung from long-term coal dust exposure—you’ll likely need medical intervention. Your provider might prescribe medications or breathing treatments to open airways and calm inflammation. Pulmonary rehab can also help you stay active and breathe easier. If scarring becomes severe, supplemental oxygen may be necessary to help your lungs do their job.

Sinus infection

Here’s the deal: not all sinus infections need antibiotics. Many clear up on their own with rest, fluids, and a few home remedies. Providers often recommend a “watch and wait” period of up to 10 days to let your immune system fight it off naturally—unless dealing with severe onset (including high fever, discharge or major facial pain) or double worsening of symptoms after initial improvement. If symptoms stick around or worsen, that’s when antibiotics may come into play.

Postnasal drip

That annoying drip down your throat? Treatment depends on why it’s happening.

• Bacterial infections: Often treated with antibiotics, decongestants, nasal sprays, and saline rinses. Chronic sinusitis may even require surgery to open blocked sinuses.
• Allergies: Avoiding triggers is key. Antihistamines, nasal sprays, or allergy shots can help keep things under control.
• Other tips: Stay hydrated, skip caffeine and diuretics (they dry you out), and consider mucus-thinning agents like guaifenesin or saline sprays to keep things moving.

Acute bronchitis

Most bronchitis cases are viral, which means antibiotics won’t help and usually aren’t needed. The infection tends to clear within a week, though the cough commonly lasts two to three weeks. If you’re wheezing or your symptoms don’t improve, your provider may prescribe an inhaler to help open your airways. Occasionally, antibiotics or steroids are used if bacteria or inflammation are part of the picture.

Pneumonia

Treatment depends on what’s behind the infection. Bacterial pneumonia usually requires antibiotics, while viral pneumonia typically clears on its own with rest, fluids, and supportive care. Managing pain, fever, and cough helps your body focus on healing. Severe cases may require hospitalization.

Cystic fibrosis

Managing cystic fibrosis takes a full toolbox. Treatments often include:

• Antibiotics to fight infections.
• Inhaled medications to open airways.
• Mucus thinners like DNAse enzymes or hypertonic saline to help you cough up phlegm.
• Oxygen therapy for advanced lung disease.
• Airway clearance techniques like deep breathing, exercise, specialized devices, or chest physiotherapy to loosen mucus and make breathing easier.

Bronchiectasis

Treatment focuses on:

• Antibiotics (oral or inhaled) to control chronic infection.
• Expectorants and mucus thinners to help clear airways.
• Bronchodilators to relax airway muscles and make breathing easier.
• Inhaled corticosteroids if asthma or COPD are also in the mix.
• Chest physical therapy—gentle percussion or vibration on the chest and back—helps loosen mucus for easier coughing.

COPD

For COPD, treatment depends on severity. Common tools include:

• Bronchodilators and steroids to relax and open airways and reduce inflammation.
• Antibiotics during flare-ups caused by infection.
• Pulmonary rehab, a program combining exercise, education, and breathing techniques.
• Oxygen therapy for when lungs can’t keep up.
• Surgery, in rare cases, for those with severe, treatment-resistant symptoms.

Fungal infections

Milder fungal infections often resolve on their own. When treatment’s needed, antifungal meds like itraconazole usually do the trick for some forms of aspergillosis. If that doesn’t work, oral corticosteroids may be used instead.

For chronic or more severe cases—such as a fungal ball in the lung—surgery may be necessary to remove it.

Tuberculosis

Treating active TB takes time and consistency. You’ll likely be on a carefully chosen antibiotic combo for several months (often four to nine). Sticking to your treatment plan is key to full recovery and preventing antibiotic resistance.

Pulmonary embolism

A pulmonary embolism (PE) is a medical emergency—don’t wait this one out. Treatment is aimed at stopping and dissolving clots:

• Anticoagulants (blood thinners) prevent clots from growing or forming new ones.
• Thrombolytics dissolve large, dangerous clots in severe cases.
• Catheter-assisted removal can physically break up or deliver medication directly to the clot.
• Vena cava filters, used in people who can’t take blood thinners, catch clots before they reach the lungs.

Prevention and long-term lung care

You can’t always dodge the germs or gunk that lead to brown mucus, but you can stack the odds in your favor. Whether your issue is a one-off infection or part of a chronic lung condition, these smart habits can help keep your airways clearer and your lungs happier in the long run.

Cut down on pollutants and allergens

Check your local air quality before heading outside, especially if pollution, pollen, or wildfire smoke levels are high. When things look bad, stay indoors or wear a respirator mask if you can’t avoid exposure (think: construction sites, city smog, or dusty workspaces).

Clean up your indoor air

What’s inside your home matters just as much. Secondhand smoke, chemical cleaners, and even mold can all irritate your lungs, especially if you already have a respiratory condition. Keep things fresh by dusting often, swapping out air filters regularly, and keeping your space smoke-free.

Quit smoking (for real this time)

No judgment, but this one’s a biggie. Smoking damages your lungs and makes mucus thicker, stickier, and harder to clear. Need a little help? For (free) support quitting, call 1-800-QUIT-NOW (1-800-784-8669) or visit Smokefree.gov.

Stay up to date on vaccines

Your lungs will thank you for a little extra protection. Vaccines for COVID-19, flu, and pneumonia can help prevent infections that hit the respiratory system hard, especially for older adults, pregnant people, and anyone with asthma, COPD, or a weakened immune system.

Hydrate and move

Simple but effective: drink plenty of water to keep mucus thin and easy to expel. And get moving—activities like walking, swimming, or even gentle stretching help loosen phlegm and keep your lungs working efficiently. (Just check with your provider if you have a chronic condition before ramping up your activity.)

Special situations

Some situations involving brown mucus can be especially tricky to diagnose and/or treat.

GERD

Sometimes, brown mucus (and that constant postnasal drip) can actually be a sign of gastroesophageal reflux disease (GERD)—a fancy way of saying stomach acid is sneaking back up into your esophagus. That acid can irritate and inflame the throat and airways, prompting your body to churn out extra mucus as a defense mechanism.

Managing GERD is often about making small, steady lifestyle tweaks: Raise the head of your bed six to eight inches, skip late-night meals, limit alcohol and caffeine, and consider losing excess weight if needed. Over-the-counter antacids or acid blockers can also bring relief. But if reflux persists, it’s time to loop in your primary care provider or an ENT (ear, nose, and throat specialist) to rule out anything more serious.

Pregnancy

Pregnancy changes a lot, including how your lungs handle infection. Because of normal shifts in immunity and lung capacity, pregnant people are more prone to respiratory infections like pneumonia and sometimes experience more severe cases. These changes (think: altered immune responses, reduced lung volume, and higher aspiration risk) make the lungs a bit more vulnerable.

When pneumonia strikes during pregnancy, treatment can be tricky. Your provider must balance what’s safe for the baby with what’s effective for you. Thankfully, the Pregnancy and Lactation Labeling Rule has made it easier for clinicians to identify which antibiotics are safe during pregnancy and breastfeeding. Most commonly prescribed antibiotics are considered safe, but they should always be used at the lowest effective dose possible.

Postinfectious cough

If you’re still hacking up brown mucus weeks after a cold or flu, you could be dealing with a postinfectious cough, a lingering side effect of inflammation in the airways. After an infection, your bronchial tubes stay hypersensitive and produce extra mucus, even though the germs are long gone.

This type of cough affects up to 1 in 4 adults after a respiratory infection and typically lasts three to eight weeks. The good news? It usually fades on its own. Most people recover without medication, proving that this annoying cough and brown phlegm are more like guests that overstay their welcome than a long-term problem.

The bottom line

Seeing any color other than clear or white in your mucus can be unsettling, but don’t panic. “In the vast majority of cases, brown mucus originates from the upper airway and is caused by treatable issues like dry air, allergies, or a resolving cold,” says Dr. Trenkle. Still, if it lingers or comes with warning signs—like heavy bleeding, chest pain, or breathing trouble—it’s time to get checked out. An ENT specialist can take a closer look at your airways, pinpoint the cause, and create a treatment plan that actually works.

Ready to breathe easier? General Medicine can help. Connect with an experienced clinician over video to discuss your symptoms and get personalized care from the comfort of home, including any prescriptions, lab orders, or referrals you need to feel better, faster.

Key takeaways

• Brown mucus doesn’t always mean an infection. It can come from old blood, smoke, dust, or even dry air, as well as more serious chronic lung conditions.
• Where it comes from matters. Brown mucus can originate in your sinuses or your lungs, depending on whether you’re coughing it up or blowing it out.
• Look out for red flags. Large amounts of blood, chest pain, shortness of breath, or symptoms that won’t quit mean it’s time to see a provider.
• Home care helps. Hydration, nasal rinses, and humidifiers can ease symptoms, but they don’t fix the root cause.
• Prevention is power. Avoid irritants, quit smoking, stay active, and keep up with vaccines to keep your lungs healthy long-term.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Pallabi Sanyal-Dey, MD.

FAQ

What does it mean if you cough up brown mucus?

Brown mucus usually means there’s old blood, dirt, or other debris mixed in with your phlegm. It can happen when your airways are irritated from a lingering infection, allergies, smoking, or breathing in pollutants or dust. Other times, it can hint at something more serious like pneumonia or chronic lung disease. If it sticks around or comes with other symptoms (like fever, chest pain, or shortness of breath), it’s worth getting checked out.

Is brown mucus a sinus infection?

Not always. A sinus infection can definitely turn your mucus darker (thanks to trapped mucus and old blood), but brown phlegm can also come from your lungs, not just your sinuses. So if you’re coughing it up instead of blowing it out your nose, the issue may be lower in your respiratory tract.

Can dehydration cause darker mucus?

It can certainly contribute. “When the body lacks enough fluids, mucus becomes thicker and more concentrated, making it appear darker,” explains Dr. Lumpkin.

Do I need antibiotics if I cough out brown mucus?

Not necessarily. Brown mucus on its own doesn’t automatically mean you need antibiotics. Many cases come from viral infections, allergies, or irritants, and antibiotics don’t help with any of those. They’re only useful if your provider confirms a bacterial infection like pneumonia. So if your symptoms drag on for more than a week or two, get worse, or you have a fever, see your healthcare provider to figure out what’s really going on.