A Guide To The 4 Stages Of Pneumonia

Pneumonia is a type of chest infection where the air sacs (alveoli) in the lungs become filled with fluid and pus, making it hard to breathe. A virus, bacteria, or fungi can cause the condition. 

Symptoms can appear over a couple of days in the case of bacterial pneumonia or several days with viral pneumonia. 

Over the following weeks, pneumonia can progress through the four stages. The duration of pneumonia varies depending on the person. Most people feel better after a few weeks, while others can take up to six months to make a full recovery. 

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What are the four stages of pneumonia?

Pneumonia has four distinct stages of infection: Congestion, red hepatization, gray hepatization, and resolution.

Keep in mind that everyone who gets pneumonia will have a different experience. You may not follow the same timeline or have the same symptoms in each stage. Let’s step through the four stages and see what they involve.

Stage one: Congestion

The first stage of pneumonia occurs around 24 hours after developing an infection in the lungs. It also lasts for about 24 hours. 

During the congestion stage, the bacteria or virus has taken hold in the lungs and caused an infection. At this point, there aren’t enough immune cells in the lungs prepared to fight the infection. 

The lungs become inflamed and red due to swelling of the alveoli and engorged blood vessels. Due to these changes, the lungs often feel heavy and congested as fluid builds up in the alveoli. 


Possible symptoms during the congestion stage include:

  • Congestion

  • Fever

  • Tiredness

  • A wet cough with sputum 

  • Chest pain 

  • A heavy feeling in the chest 


Doctors can detect and treat pneumonia during the congestion stage. 

Most people can manage pneumonia at home, especially during the early stages of infection. 

The recommended treatment for pneumonia depends on whether a virus, bacteria, or fungi are the cause. Your doctor may treat:  

  • Bacterial pneumonia with antibiotics

  • Viral pneumonia with antivirals, although it’s usually managed with supportive care 

  • Fungal pneumonia with antifungals

You can also take over-the-counter medications, such as aspirin or ibuprofen, to manage your symptoms and bring down a fever. It’s important to get plenty of rest and drink enough water.

It’s essential to see a healthcare professional to start treatment as soon as possible. This could minimize the effect of the later pneumonia stages. 

Stage two: Red hepatization 

The second stage of pneumonia occurs around two to three days after the infection develops. It usually lasts between two to four days.

During this stage, red blood cells and immune cells travel to the alveoli to prepare to fight the infection. Since there are more red blood cells, the lungs may appear red. The lungs also become dry, airless, and firm, often resembling the liver. 

These changes make it harder for the alveoli to work.


Possible symptoms of the red hepatization stage include:

  • Feeling tired as your body works to fight the infection

  • Producing less sputum during coughing

  • Shortness of breath  

Stage three: Gray hepatization 

The third stage of pneumonia usually happens on days four to six of infection, lasting four to eight days. 

At this point, the lungs continue to resemble the liver. However, they develop a dark gray color. This is because many of the red blood cells break down.

Another important thing that happens is that macrophages, a particular type of immune cell, enter the lungs. 


You’ll typically feel worse during this stage, but treatment can continue to help. 

Signs of a medical emergency include:

  • Blue lips or nails

  • Severe shortness of breath 

  • Shallow breathing

  • Dizziness

  • Confusion

These symptoms don’t occur in everyone. They indicate hypoxia, which means the oxygen levels in the blood are too low. It is crucial to seek emergency medical care if you experience these symptoms. 


The treatment of pneumonia during the red and gray hepatization stages is similar. Again, most people can recover at home by resting and continuing their prescribed medications. 

However, if you develop hypoxia or have a lot of difficulty breathing, you may need to spend time in the hospital. 

Medical interventions in the hospital include:

  • Supplemental oxygen or a ventilator to help you breathe

  • Intravenous medicine if you’re too unwell to swallow pills 

  • Nutrition through an intravenous line

  • Draining the fluid around your lungs

  • Antibiotics if the pneumonia is bacterial 

Stage four: Resolution

The final stage of pneumonia occurs between days eight to ten. 

This is the recovery phase of pneumonia, where the immune cells and enzymes fight the infection, allowing the alveoli to work better.

The macrophages clear pus from the infected area. Your lungs may be left with scar tissue when the infection clears.


You’ll typically start to feel better and have more energy as the immune cells clear the infection. More coughing and sputum production are normal as your lungs work to clear the accumulated fluid and debris. 


You should continue the treatment that began in the earlier stages for as long as the doctor prescribed it. If you feel better and stop taking your antibiotic early, pneumonia can return and become resistant to the medication. 

The lowdown 

As pneumonia progresses, it has four stages: Congestion, red hepatization, gray hepatization, and resolution. You’ll typically feel worse during the first three stages before feeling better during the final stage when the immune cells clear the infection.

While the recommended treatment is generally the same in all stages, it’s essential to see a doctor and start treatment as soon as possible during the early stages. This lessens the impact of pneumonia in its later stages.


At what stage of pneumonia do you cough up blood? 

A possible symptom of lung infections such as pneumonia is coughing up blood-stained mucus. There is no specific stage at which you only cough up blood, so look for this symptom throughout the illness.

Seek medical care if you: 

  • Cough up blood in mucus for more than a week

  • Experience chest pain

  • Have extreme shortness of breath

  • Have a fever over 101 degrees

  • Notice weight loss

  • Experience heavy night sweats

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