I finally understand my therapy. The app reminds me, answers my questions — and I don't feel alone with it anymore.
Medically reviewed guide · Last updated: 1 August 2026 · Reading time: approx. 9 min
Phlegm: What Colour, Amount and Duration Say About Your Airways
At a glance
Phlegm — sputum, in clinical language — is bronchial mucus that you cough up.Every healthy lung produces a small amount of mucus each day; it only becomes visible when more of it forms or when it turns thicker.
The colour is a weak signal, not proof.Yellow or green phlegm shows that immune cells are present in the mucus — with a viral infection just as much as with a bacterial one.
More important than the colour are the amount, the duration and the accompanying symptoms.A productive cough lasting more than eight weeks counts as chronic and should be assessed.
Coughing up phlegm every morning is not “normal” for people who smoke, but often the first visible sign of chronic bronchitis or of COPD beginning.
Get checked straight away if you havepink, frothy phlegm with breathlessness (call 112, the emergency services in Germany), blood in your phlegm, breathlessness with a high fever, sudden breathlessness with chest pain, or new phlegm while your immune system is severely weakened.
The colours compared — and what they really mean
This table is a guide, not a diagnosis. Colours shade into one another, change over the course of an infection and, taken on their own, say nothing about whether an antibiotic is needed.
Appearance
What is often behind it
Typical accompanying signs
First step
Clear to whitish, fairly thin
Viral airway infection, irritation from smoke, dry air or an allergy
Scratchy throat, blocked nose, no fever or only a moderate one
Wait it out, drink plenty, avoid irritants
White and thick, hard to cough up
Chronic irritation of the bronchi, common in people who smoke; also in asthma
Morning cough, a feeling of tightness
Get it checked at a GP practice if it happens daily
Yellow to green
A lot of immune cells in the mucus — with viruses as with bacteria
A course over days, often changing colour clear → yellow → green → clear
Not a reason for an antibiotic on its own; watch the fever and your general condition
Brown or grey-brown
Old blood components, soot and tar particles in people who smoke, dust exposure
Years of coughing, breathlessness on exertion
Assessment at a GP practice, lung function test
Pink and frothy
Fluid from the lung tissue — a warning sign of acute heart failure
Severe breathlessness, restlessness, often worse lying down
Emergency: call 112
Bloody or streaked with blood
A burst small vessel from violent coughing, an infection — more rarely serious causes
Fresh red, often mixed in frothy
Always get it checked, even if it happens only once
Table scrolls to the right
Cough, phlegm, inhalers — documented instead of guessed
Keep the course and your medicines in one place — free of charge in the brite app.
The most common reason for newly appeared phlegm is an infection of the lower airways. The lining of the bronchi responds to viruses by producing more mucus; after two to three days the cough turns from dry to productive. With acute bronchitis the phlegm is often clear at first, then yellowish, later greenish and clear again at the end — this run of colours is the normal course of an immune response and not a sign that “it has got worse”. A cough like this is allowed to be stubborn and lasts two to three weeks in many people. How to tell a cold apart from flu and COVID is set out in the guide Cold, flu or COVID.
Chronic bronchitis and COPD: the “smoker's cough”
A cough with phlegm on most days over at least three months in two consecutive years counts by definition as chronic bronchitis. For many people it stops there; in some, a permanent narrowing of the airways is added — and then it is called COPD.
Morning phlegm is typical: mucus collects overnight and coughing it up after getting up becomes a habit — and with that, invisible. If you smoke and answer yes to the question “Do you cough anything up in the morning?”, that is not a harmless ritual but a finding. Stopping smoking is the only measure proven to slow the loss of lung function in COPD.
Asthma: phlegm as a sign of inflamed bronchi
In asthma, a dry irritable cough with wheezing on breathing out is usually in the foreground. But thick, glassy phlegm does occur — especially after an attack or when the ongoing treatment is poorly adjusted. If the phlegm increases while your need for the reliever inhaler rises at the same time, that is a signal to review the treatment.
Pneumonia
Pneumonia differs from an ordinary infection not in the colour of the phlegm but in your general condition: a high fever, shivering, fast breathing, marked weakness, often chest pain that comes with breathing. If breathlessness is added, or your condition worsens after an initial improvement, that needs examining promptly — in older people a fever may be absent.
Bronchiectasis: when large amounts become the rule
Bronchiectasis means permanently widened, pouched bronchi in which mucus builds up and bacteria settle. Typical features are large amounts of phlegm over years, often depending on your position, along with repeated infections. Among other things it develops after severe pneumonia or with immune deficiencies. If you regularly cough up considerably more than a tablespoon of mucus a day, you should raise it — there is targeted respiratory physiotherapy for that.
Heart failure: the pink, frothy special case
Pink, frothy phlegm does not arise in the bronchi but comes from the air sacs: in acutely decompensated heart failure, blood backs up in the vessels of the lungs and fluid passes into the lung tissue. It comes with severe breathlessness, restlessness, pallor and the typical worsening when lying down. That is an emergency and no case for a mucolytic. The milder form counts too: if you cough at night, need several pillows to sleep and have swollen ankles, you should have your heart thought about.
When the mucus does not come from the lungs at all
If secretions from the sinuses run down the back of your throat, you clear your throat and cough them up — it looks like phlegm but comes from above. The clues are pressure in the face, a blocked nose and symptoms that increase when you lie down. Rising stomach acid can also cause a chronic cough with a feeling of mucus. Both are treatable — but treatable differently from bronchitis.
Blood in your phlegm: the one case that cannot wait
As soon as blood becomes visible in your phlegm — as red streaks, as a rust-brown shade or as fresh, frothy red — you leave the territory of self-assessment. The most common causes are harmless: a burst vessel after violent coughing fits, or a badly inflamed lining. That is exactly why the dangerous reflex to dismiss it arises.
The reason for the clear rule “always get it checked” is not the probability but the consequence: the rarer causes include lung tumours, pulmonary embolism and tuberculosis — conditions in which recognising them early makes the difference. If you cough up larger amounts of blood, if breathlessness is added or if you become dizzy, that is an emergency.
Do not wait to see whether it “goes away by itself” Blood in your phlegm justifies a prompt appointment, even if it only happened once. On anticoagulants that applies all the more — but never stop them on your own, discuss it medically instead. How to keep your active ingredients to hand is set out under Keeping a medication list.
Self-observation: what a week of documentation reveals
These observations do not replace a diagnosis. But they turn “I just cough a lot” into a description a practice can work with.
Estimate the amount roughly: a teaspoon, a tablespoon or more per day? Large amounts point more towards bronchiectasis or a pronounced chronic bronchitis.
Note the time of day: almost all of it in the morning? Spread across the day? Mainly at night when lying down? Night-time symptoms turn attention to the heart, reflux or asthma.
Record the colour and consistency — and specifically the course of it, not the single finding. A change of colour over days is normal; a constant discolouration over weeks is not.
Collect the triggers: cold air, smoke, dust at work, exertion, pets. Repeated patterns are worth more than any single observation.
Count the duration and note the accompanying symptoms: since exactly when? Plus fever, breathlessness, weight loss, night sweats and how much you can manage — these details steer the urgency more strongly than the phlegm itself.
Warning signs: when not to wait
Pink, frothy phlegm with severe breathlessness
Blood in your phlegm — even once and even in small amounts
Breathlessness at rest, pale or bluish lips, very fast breathing
A high fever with shivering, confusion or marked weakness
A productive cough that lasts longer than eight weeks
Unintended weight loss, night sweats or increasing hoarseness
New or changed phlegm while on chemotherapy, long-term steroid treatment or other immunosuppression
When to call the emergency services Pink, frothy phlegm with severe breathlessness is an emergency — call 112 (emergency services in Germany) and sit the person affected upright. The same applies to sudden breathlessness with chest pain and to larger amounts of coughed-up blood.
The treatment pathway: step by step
With phlegm, the approach goes from simple to elaborate. The order depends on how long the symptoms have been going on and how you are doing overall.
Acute and without warning signs: wait and support. Drink enough, moist room air, avoid irritants, take it easy. Most infections need time, not medicines.
Assessment at a GP practice for a fever over several days, breathlessness, blood in your phlegm or a cough lasting more than three weeks: history, listening to your chest, often oxygen saturation and inflammatory markers.
Lung function and imaging. For chronic phlegm, spirometry is part of the picture — it distinguishes COPD from asthma. Imaging follows if pneumonia or bronchiectasis is suspected.
Targeted treatment instead of a scattergun. Antibiotics only work against bacteria; in viral bronchitis they bring no benefit, but they do bring side effects and resistance.
Specialist care. For chronic phlegm, repeated infections or abnormal imaging, respiratory medicine takes over; with bronchiectasis, respiratory physiotherapy is added.
The medication angle: what influences cough and phlegm
An ACE inhibitor cough is dry — that is the decisive distinction
Around one in ten people who take an ACE inhibitor such as ramipril develops a persistent irritable cough. It can appear weeks to months after treatment starts and is therefore often not connected with the blood pressure medicine. The decisive point for making sense of it: this cough is typically dry and tickly — it does not produce any phlegm.
If you cough on an ACE inhibitor and cough up mucus every day, the medicine only explains part of the story — the phlegm then needs an explanation of its own. Conversely, for a purely dry cough it is worth discussing a switch; a change to a sartan is a common option. The treating practice makes that decision.
Mucolytics: an honest appraisal
Over-the-counter mucolytics are among the best-selling preparations — and among those with the thinnest evidence. On current knowledge the effect in acute airway infections is modest at best; drinking enough and inhaling salt solution or water vapour is widely regarded as equivalent. Giving them a try is defensible, but it does not replace an assessment if the phlegm goes on for weeks. In COPD, ongoing treatment can reduce flare-ups in individual cases — that is a medical judgement.
Inhaler technique: the underestimated factor
When sprays do not work, surprisingly often it is not the active ingredient but the way it is used: pressed too early, breathed in too fast, breath not held, rinsing the mouth forgotten. The active ingredient then lands in the throat instead of the bronchi.
That applies to fast-acting salbutamol just as much as to long-acting maintenance medicines of the tiotropium type. Before a treatment is written off as “not working”, it is worth having your technique checked — the guide Inhaling correctly explains it step by step.
Immunosuppression: a different yardstick for the same symptoms
If you take prednisolone over a longer period, receive other immunosuppressants or are going through chemotherapy, you need to have new phlegm assessed sooner. Steroids damp down the inflammatory response: a fever can turn out lower and your general condition can look unremarkable for longer while pneumonia is already spreading.
Have all your active ingredients to hand. With a cough that brings up phlegm, your medication list is a diagnostic tool: ACE inhibitors, beta blockers, anticoagulants, immunosuppressants and inhaled medicines change the assessment — see Keeping a medication list.
Eight weeks of coughing — or is it twelve by now?
Duration, phlegm and triggers documented: your appointment gets specific instead of vague.
Stopping smoking — the single most effective measure. For many people the morning phlegm reduces within weeks to months; the loss of lung function slows down at any age.
Take up the vaccinations on offer — flu, pneumococcus and COVID-19 lower the risk of severe illness in chronic lung disease.
Drink enough and humidify the air — thinner mucus is easier to cough up. Unspectacular, but with a very good benefit-to-risk ratio.
Have your inhaler technique checked once a year — it deteriorates without you noticing. Demonstrate how you use it rather than describing it.
Take irritants at work seriously — dusts, vapours and gases are a recognised cause of chronic bronchitis. Protective measures are not over-eagerness.
Your inhaler only works if you take it
Reminders for inhaled medicines and antibiotics — on time, without having to think.
No. The green colour comes from an enzyme released by immune cells, which migrate in during viral infections just as they do in bacterial ones. Green phlegm on its own does not justify an antibiotic. Whether one is needed is decided by your general condition, the course of the fever and the examination findings.
A cough is usually counted as acute up to three weeks, as subacute up to eight weeks and as chronic beyond that. A productive cough lasting more than eight weeks should be assessed, even if you otherwise feel well. For chronic bronchitis there is an additional definition: a cough with phlegm on most days over three months in two consecutive years.
Widespread yes, normal no. Coughing up phlegm every morning shows that the self-cleaning of the bronchi is disturbed, and it is often the first visible symptom of chronic bronchitis or of COPD beginning. A lung function test clarifies whether the airways are narrowed.
ACE inhibitors cause a stubborn irritable cough in some of the people treated with them, and it can appear for the first time months after treatment starts. This cough is typically dry and produces no phlegm. If you cough up mucus every day, that needs an additional explanation. Never stop the medicine on your own.
The evidence for over-the-counter mucolytics in acute airway infections is limited and the benefit modest at best. Drinking enough and inhaling salt solution or water vapour is widely regarded as equivalent. Giving them a try is defensible, but it does not replace an assessment.
Pink, frothy phlegm together with severe breathlessness points to fluid in the lung tissue caused by acute heart failure. That is an emergency: call 112 and position the person affected upright.
A productive cough has a job to do: it moves secretions out of the airways. Cough suppressants are therefore usually not sensible when you have phlegm, and at most they are considered briefly for the night. If coughing it up is very exhausting, breathing techniques and secretion clearance help more.
Gesundheitsinformation.de (IQWiG): cough and acute bronchitis — German source. Accessed 2026.
gesund.bund.de: cough, COPD and pneumonia — German source. Accessed 2026.
MSD Manual, Consumer Version: cough and sputum, haemoptysis. Accessed 2026.
German S2k guideline on the diagnosis and treatment of adult patients with cough (DGP, AWMF register) — German source. Accessed 2026.
German National Disease Management Guideline (NVL) on COPD and the S2k guideline on COPD (DGP, AWMF register) — German source. Accessed 2026.
Summaries of product characteristics for the active ingredients mentioned (ramipril, salbutamol, tiotropium, prednisolone). Accessed 2026.
This article is for general information and does not replace medical advice, diagnosis or treatment. The self-observations described are a guide only and not a diagnosis. If you have pink, frothy phlegm with breathlessness, blood in your phlegm, breathlessness at rest, or a high fever with marked weakness, please contact a doctor or the emergency services.
