Farmer’s Lung – Causes, Symptoms & Treatment


Farmer ‘s lung occurs primarily in people who work with plant residues. These include hay, straw and dry fodder. If left untreated, it can become chronic and lead to death.

What is a farmer’s lung?

Farmer’s lung is an inflammation of the alveoli caused by bacterial and mold spores (exogenous allergic alveolitis ). The immune system identifies the inhaled (“exogenous”) spores and their components (allergens) as foreign to the body.

The triggered allergic reaction is an “excessive response” of the organism. The result is inflammation of the air sacs in the lungs, which can be acute or chronic. Chronic inflammation of the air sacs in the lungs may develop into what is known as pulmonary fibrosis :

The increased formation of connective tissue impairs the elasticity of the lungs and thus breathing. Due to the connective tissue, the lungs are also less and less able to supply the blood with sufficient oxygen. The decrease in oxygen content caused in this way manifests itself in reduced physical and mental resilience. As pulmonary fibrosis progresses, shortness of breath also occurs at rest.


The storage of plant residues can lead to a strong proliferation of bacteria and mold . This process is promoted by warm and humid conditions. For example, if the weather is mild and rainy after mowing the grass, mold deposits will soon form inside the stored hay. When the mowing material is moved again, the fungal spores are easily released into the air and can be inhaled.

However, the spread of fungal and bacterial spores is also possible during the grain harvest, when spreading the bedding in stables and when producing feed in the silo. Other possible sources include turning compost heaps and harvesting and storing wood chips. Their small size allows the spores to penetrate the alveoli of the lungs and provoke inflammatory processes.

Symptoms, Ailments & Signs

The acute form of farmer’s lung usually manifests itself in cough , shortness of breath , chills and fever . Chest tightness, a runny nose and a general feeling of weakness are also described. The fever with temperatures up to 40 °C can occur in fits and starts. Some patients complain of brown-yellow sputum and burning in the throat.

Rarely, bright red, frothy blood is coughed up . These symptoms appear just a few hours after contact with the inflammatory spores. They usually subside overnight, only to reappear the next time the allergens affect them. In some of those affected, this symptom, which is sometimes described as flu-like, is not very noticeable (subacute).

It is observed, for example, in people whose organism reacts less sensitively to fungal and bacterial spores. Others are only exposed to a low level of spores, so that the symptoms are correspondingly weaker or even non-specific. Complaints such as loss of appetite , insomnia and coughing can be an expression of many diseases.

If the spores act regularly over many years, the inflammatory processes they trigger manifest themselves in a further deterioration in the general condition and in weight loss. It is an indication of the progressive formation of connective tissue in the lungs (pulmonary fibrosis) and thus of the transition of the farmer’s lung into the chronic phase.


The blood of sick people shows a significant increase in white blood cells ( leucocytosis ). T – lymphocytes are increasingly found in the lungs, which is an expression of the inflammatory process taking place there. As so-called killer cells, they serve to recognize invading foreign substances and eliminate them. An important symptom of farmer’s lung is the presence of so-called immunoglobulin G (IgG) antibodies in the blood.

These are also formed when viruses , bacteria or foreign substances have entered the organism. In the pulmonary function test, a reduction in the distensibility of the lungs and chest indicates a restrictive ventilation disorder. It is explained by the increasing formation of connective tissue between the alveoli and the scarring of the walls of the alveoli.

An acute farmer’s lung is expressed in the X-ray image by accumulations of fine spots. The reduction in the diffusion capacity of the lungs indicates that less oxygen can be absorbed by the organ and delivered to the blood. Computer tomography of the lungs (thoracic CT) and bronchoscopy (lung reflection) are also used . Between 1 and 17% of patients die as a result of farmer’s lung disease. The stress on the cardiovascular system can lead to heart failure.


In the worst case, a farmer’s lung can be fatal. However, this course only occurs if the farmer’s lung is not treated. In most cases, patients suffer from the symptoms of a common cold or those of a fever. These include chills and fever.

However, there is severe shortness of breath and coughing, which is associated with a strong build-up of mucus. The flu symptoms also cause a feeling of weakness. Physical work is hardly possible anymore. The fever can reach very high temperatures and become extremely dangerous for the body.

Temperatures of up to 40 degrees Celsius are possible. In severe cases, coughing up blood occurs , which leads to a panic attack in most sufferers. The farmer’s lung also leads to loss of appetite and sleep problems. This can lead to underweight and dehydration. Both conditions are very dangerous for the body and must be avoided.

Farmer’s lung usually develops over several years and is manifested by more and more frequent problems with the lungs. A specific treatment is not possible. However, the symptoms can be prevented if contact with the triggering substances is avoided. The farmer’s lung will improve on its own over time, but full recovery will not occur.

When should you go to the doctor?

In the case of a farmer’s lung, a doctor must be consulted in any case. This condition must always be treated by a medical professional as it does not heal on its own. In severe cases, farmer’s lung can also lead to the death of the person concerned. The doctor should be consulted if the patient has a high fever and continues to have chills.

A very strong cough with bloody sputum can also indicate farmer’s lung and should be examined by a doctor. The symptoms are often not permanent, but keep coming back. Insomnia or loss of appetite can also be a sign of the condition and need to be investigated if they occur over a long period of time. An examination should always be carried out, especially in the case of chronic complaints.

Farmer’s lung can usually be identified by an internist or general practitioner . Further treatment is then carried out by taking medication. In order to prevent further complaints, the affected person should always wear respiratory protection. In some severe cases, patients also need psychological treatment.

Treatment & Therapy

There is currently no cure through medication or surgery. The shorter the exposure time to the allergens , the lower the risk of permanent changes in the lung tissue. The disease can be brought to a standstill by this so-called allergen avoidance.

These can be, for example, the immunoglobulins mentioned. Cortisone can be administered to alleviate inflammation that has already occurred . Representatives of this class of substances promote the formation of white blood cells, which are increasingly produced during inflammatory processes. At the same time, however, they inhibit the release of substances in the body cells that are directed against foreign proteins (i.e. allergens).

The latter enter the human organism via the inhaled fungal and bacterial spores. The immunosuppressive (suppressing the body’s own immune system) and anti-allergic effect of cortisone play a decisive role in alleviating the symptoms described. The drug has a decongestant effect on the mucous membranes of the airways, relaxes the bronchial muscles and reduces the formation of bronchial mucus.

However, the positive effects sometimes only set in after a delay of several days. For patients in whom the disease has progressed to a chronic stage or pulmonary fibrosis, therapeutic measures to actively improve respiratory performance are recommended: These include exercise, conditioning and strengthening programs.

A healthy diet and psychotherapeutic treatment also have a beneficial effect. A lung transplant in the case of severe pulmonary fibrosis leads to a five-year survival rate of around 50%. It is recommended under certain conditions.

Outlook & Forecast

Patients with farmer’s lung generally have a good prognosis. If the disease is recognized and treated early, a rapid improvement in symptoms can be achieved. Cough, shortness of breath, and other symptoms usually subside once the cause of the condition is eliminated and drug treatment is initiated.

Acute farmer’s lung can in some cases lead to heart failure and thus death of the patient. A chronic disease develops insidiously and also places a considerable strain on the cardiovascular system. Symptoms such as breathing difficulties and pain increase in intensity over the course of the disease and permanently impair well-being. In the long term, untreated chronic farmer’s lung is also fatal.

Coughing up blood and high fever can trigger a panic attack and cause mental problems in those affected. Farmer’s lung can also cause loss of appetite and sleep problems, which further worsen the general condition.

Nevertheless, the outlook and prognosis are generally positive. Assuming early treatment, farmer’s lung usually progresses well and does not result in any further health problems for those affected. Damage to the lungs that has already occurred must be treated symptomatically.


Basically, the duration of handling plant residues should be kept as short as possible. Certified breathing masks with protection level P2 also help to keep dust that may be thrown up away from the lungs. The particle filter mask FFP2/3 is recommended. Commercial protective masks are not effective enough. Combine harvester operators should keep the control cabs closed at all times. They may only be ventilated using systems that can keep dust contaminated with spores away.

Before bringing in the hay stored in the meadows, it should be turned over several times. This is especially true after damp and mild weather conditions. A possible measure to reduce dust when handling dry food is to mix it with a little vegetable oil.


In most cases, the affected person has no options for aftercare in the case of a farmer’s lung. The disease cannot be completely treated and in most cases significantly reduces the life expectancy of those affected. Self-healing does not occur either, so that the farmer’s lung can only be treated purely symptomatically.

The triggers of the disease should be avoided at all costs so as not to put additional strain on the patient’s lungs. In many cases, those affected are dependent on taking cortisone. However, there are severe side effects that should also be treated.

When taking it, it is therefore important to ensure the correct dosage and regular intake in order to prevent further complications. The respiratory tract must be relieved, so that the person concerned should not smoke. In order to increase the performance of the lungs again, the patients can carry out various exercises, whereby a healthy lifestyle with a healthy diet can generally have a positive effect on the course of the farmer’s lung.

In the case of severe or serious symptoms, those affected are often dependent on the help of their fellow human beings in everyday life. Above all, loving care by one’s own family has a positive effect on recovery.

You can do that yourself

Farmer’s lung is a dangerous disease that can be fatal if left untreated. Those affected should therefore not treat the symptoms themselves, but should consult a doctor promptly.

The best form of self-help is complete allergen avoidance. The disorder usually develops slowly over years and can be stopped in its progression by consistently avoiding the causative substances. The symptoms then very often improve considerably over time, even if a complete regeneration of the damaged lung cannot be expected.

Simple measures can often help to reduce the stress. It is essential for farmers to wear a quality P2 face mask when working with hay, straw and other dried grasses. If you handle dry food, you can moisten it slightly or add vegetable oil to prevent excessive dust formation.

However, if avoiding the allergens is not possible, a professional reorientation must be considered in good time, at least in severe cases. Since farmer’s lung is a recognized occupational disease, those affected have relatively good social security. Self-employed farmers can get advice from their association, employed helpers in agriculture can get advice from their trade association.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.