Blood that comes up when you cough typically looks bubbly or frothy and is mixed with mucus or saliva. It can appear bright red, pink, or rust-colored, and most of the time it shows up in small amounts. That frothy quality is the key visual feature: because the blood passes through your airways, it picks up tiny air bubbles on the way up, giving it a foamy texture you won’t see with blood from other sources.
What It Actually Looks Like
The appearance ranges widely depending on how much blood is involved and where in the lungs or airways it’s coming from. At the mild end, you might notice thin red or pink streaks running through otherwise normal-looking phlegm. This blood-streaked sputum is the most common presentation, and many people first spot it on a tissue after a coughing fit.
When more blood is present, the sputum turns uniformly pink or red and has a distinctly frothy, almost sudsy consistency. Think of the texture of saliva with tiny bubbles throughout, but tinted red or salmon-pink. In rarer and more serious cases, you may cough up what looks like pure bright red blood with visible foam on the surface. The color stays on the brighter end of the spectrum because the blood has been in contact with oxygen in your lungs.
Rust-colored or brownish sputum usually means the bleeding happened hours or even days earlier. The blood has had time to break down, shifting from red to a darker, more oxidized tone. This older blood is often thicker and may look like dark streaks or clumps within mucus.
How It Differs From Vomited Blood
One of the most common points of confusion is whether the blood came from your lungs or your stomach. The two look quite different. Blood coughed up from the respiratory tract is usually bright red and frothy. Blood vomited from the digestive tract tends to be dark red or brown, sometimes resembling coffee grounds, and often contains food particles. Vomited blood also has an acidic quality because it has been exposed to stomach acid, while coughed-up blood tastes more metallic and salty.
The sensation matters too. Coughing up blood is preceded by a tickle or irritation in the chest or throat and comes up with a cough. Vomiting blood involves nausea and abdominal discomfort and comes up with a retching motion. If you’re unsure which one you experienced, that context helps a doctor figure it out quickly.
Blood That Isn’t Really From Your Lungs
Sometimes what looks like coughed-up blood actually originates from your mouth, nose, or throat rather than your lungs. Doctors call this pseudohemoptysis. Bleeding gums, a nosebleed that drains backward down the throat, or a small ulcer on the tongue or tonsils can all produce blood that you then cough or spit out. The clues that point to these sources include little or no actual coughing, a history of gum disease or frequent nosebleeds, and visible sores or irritation in the mouth or nasal passages.
If the blood appears only when you spit (not during a deep cough), and you notice bleeding gums or a recent nosebleed, the source is probably above the lungs.
Common Causes
Respiratory infections are the single most common reason people cough up blood, accounting for roughly 19% of outpatient cases and 23% of cases serious enough for hospitalization. A bad chest cold, bronchitis, or pneumonia can inflame the airways enough to cause small amounts of bleeding that mix with mucus.
Beyond infections, the other frequent causes are lung cancer (about 4% of outpatient cases but nearly 18% of inpatient cases), bronchiectasis (a condition where the airways become permanently widened and damaged), and chronic obstructive pulmonary disease (COPD). Blood-thinning medications also contribute, showing up in roughly 13.5% of hospitalized cases. Worldwide, tuberculosis remains the leading cause and dominates in countries where the disease is more common.
Perhaps the most striking statistic: in 20% to 50% of cases, no cause is ever found even after imaging and direct examination of the airways. These cases, called cryptogenic, typically involve small amounts of blood that resolve on their own.
How Much Blood Matters
The volume of blood you see is an important signal. A few streaks in your phlegm, while worth getting checked, is a very different situation from coughing up spoonfuls of bright red blood. Small amounts are far more common and often linked to treatable infections or minor airway irritation.
Large-volume bleeding, sometimes called massive hemoptysis, can block your airways, cause your oxygen levels to drop dangerously, and lead to significant blood loss. This is a medical emergency. You should call emergency services if you’re coughing up more than a few teaspoons of blood, or if the bleeding is accompanied by chest pain, severe shortness of breath, dizziness, lightheadedness, fever, or blood appearing in your urine or stool.
What Happens at the Doctor’s Office
When you report coughing up blood, doctors typically start with a chest X-ray to look for obvious problems like infections, masses, or fluid in the lungs. If the X-ray doesn’t reveal a clear cause, a CT scan provides a much more detailed view of the lung tissue and airways. In some cases, a bronchoscopy is used, where a thin camera is passed through the nose or mouth into the airways to directly visualize the source of bleeding.
Your doctor will also ask specific questions about the appearance of the blood: its color, whether it was frothy or clumped, how much there was, and whether it came up with a cough or with vomiting. Keeping a mental note of these details, or even taking a photo of the sputum on a tissue, gives your doctor useful information for narrowing down the cause.
Even a small amount of blood in your sputum warrants a medical visit. Most causes are treatable, and early evaluation rules out serious conditions faster than waiting to see if it happens again.