Many people with allergic bronchopulmonary aspergillosis (ABPA) also live with bronchiectasis, and the symptoms can overlap so much that it’s difficult to know what’s flaring. This guide explains what is happening inside the lungs, the typical signs of each condition, and how to judge when to seek help.

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1. What exactly happens during an ABPA flare?

ABPA is an allergic immune reaction to Aspergillus in the airways.
The fungus is usually present in tiny amounts, but the immune system over-reacts to it.

During a flare:

• The immune system releases large amounts of inflammatory chemicals (especially IgE and eosinophils).

• Airways become swollen, narrow and sticky.

• Thick, glue-like mucus forms and can block off airway sections.

Typical symptoms of an ABPA flare

• Increased wheeze, chest tightness or asthma-like symptoms

• Shortness of breath, sometimes sudden

• Very thick, sticky, tenacious sputum

• Mucus plugs — sometimes shaped like soft tubes or “casts” of an airway

• Drop in peak flow or lung function

• IgE levels rising (but this may lag behind symptoms by days or weeks)

Colour of mucus in ABPA

• Often golden-brown

• Can be brown or even dark brown if old mucus is clearing

• May contain small black dots (fungal elements) but this can also appear in bronchiectasis

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2. What happens during a bronchiectasis flare?

Bronchiectasis is a structural lung condition. The airways are wider and more damaged, meaning mucus gets trapped more easily.

During a flare:

• The airway lining becomes irritated or infected.

• Mucus production increases.

• Trapped mucus becomes a breeding ground for bacteria.

• Breathing may be heavier simply because of mucus load.

Typical symptoms of a bronchiectasis flare

• Increase in sputum volume

• Change in sputum colour (yellow, green, brown)

• Worsening cough

• Feeling more tired, feverish, or run down

• Chest tightness from mucus but not usually dramatic wheeze

• No immediate change in IgE levels

Bronchiectasis and brown sputum

• Brown sputum is common when old blood, dried mucus or debris is being cleared.

• After a lung bleed, blood changes colour as it ages:

  • Fresh = bright red

  • 24–48 hours = dark red

  • After a few days = brown, tar-like, sticky

This often appears suddenly after you think everything has settled.

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3. Comparing the two conditions side-by-side

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4. Understanding brown sputum properly

Brown sputum doesn’t always mean ABPA.

It can be:

• Old blood breaking loose

• Dried mucus from bronchiectasis

• A mixture of dried secretions and oxidised blood proteins

• Debris from a recently cleared airway infection

This is why a single brown plug — especially after a bleed — is rarely a sign of ABPA on its own.

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5. When you should ask for help

Contact your specialist if you notice any of these:

• Several days of brown plugs or repeated mucus casts

• Dramatically increased wheeze

• Peak flow drop >20% from your baseline

• Fever, chills, or sudden tiredness

• Breathlessness that feels “different” from normal

• A major change in your usual bronchiectasis pattern

• New chest pain

Seek urgent help if:

• You cough up fresh bright red blood

• You feel suddenly very breathless

• You cough up a large amount of blood-stained sputum

• You have signs of severe infection (rigors, high fever, confusion)

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6. And what about IgE?

IgE is helpful, but has limitations:

• It rises slowly — sometimes days or weeks after symptoms appear.

• It can stay stable at your “baseline” even when mild inflammation is happening.

• A stable IgE level is reassuring, but it does not rule out a flare.

Think of IgE as a trend, not an immediate alarm light.

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7. The real-world takeaway

• Bronchiectasis = more mucus, infected/inflamed feeling, colour change.

• ABPA = allergic response, wheeze, plugs, sudden breathing changes.

• Brown sputum alone is not enough to diagnose either way.

• After a bleed, brown sputum is expected for days as the airway clears.

Learning your own pattern takes time. Even experienced patients still contact their team if something feels wrong — and that’s always the safest approach.

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