Multiple Chemical Intolerance – Causes, Symptoms & Treatment

Multiple chemical intolerance

In the case of multiple chemical intolerance , which is also referred to as MCS , those affected react to different and unrelated chemicals and substances, sometimes with severe symptoms. The course of the disease is chronic and can worsen over time. MCS limits the quality of life and can lead to disability.

What is Multiple Chemical Intolerance?

The multiple intolerance to chemicals characterizes a syndrome that has been known since the 1980s and is characterized by multiple intolerances to many volatile chemical compounds. In English-speaking countries it is also referred to as MCS ( Multiple Chemical Sensitivity ).

MCS was the subject of much controversy in the 1980’s and 1990’s as to the cause of the condition. It was discussed whether the multiple intolerance to chemicals should be assigned to the field of toxicology or psychosomatics . It has been observed that greater exposure to chemicals often leads to the onset of MCS.

Even the smallest amounts of volatile substances such as fragrances, exhaust fumes, cigarette smoke or solvents cause MCS patients to suffer from non-specific and diverse symptoms that greatly reduce their quality of life. However, the symptoms disappear immediately if the triggering substances are avoided.


The causes of the multiple chemical intolerance are not known. Today only attempts at explanations are made in order to be able to interpret the complex of symptoms. The majority of sufferers were found to have initially been exposed to overexposure to chemicals. These include formaldehyde, solvents or biocides. In most cases, the triggering chemicals are also neurotoxic. Nevertheless, the pollution is reversible in the majority of cases.

In a few cases, chemical sensitivity becomes chronic and worsens even further to full-blown MCS. Over time, more and more chemicals are added that are not tolerated. Other factors must also be present for MCS to develop. In addition to genetically caused faulty detoxification reactions of the body, psychosomatic factors, existing allergies and other underlying diseases are discussed.

Today it is assumed that the disease is multifactorial, with toxicological and psychosomatic factors being equally involved. Risks are diseases of the respiratory tract , allergies, food and drug intolerance , stress , anxiety disorders or post-traumatic stress disorders .

The status of research into the causes is still very unsatisfactory for those affected because they often feel that they are not being taken seriously. Due to the lack of clarity in the assignment to this syndrome, different prevalence rates for chemical intolerance were determined in different countries. While the prevalence in the USA is 3.9 percent, a value of 0.5 percent is given for Germany. This also makes it difficult to determine the cause of this disease. As a result, the prerequisites for a causal treatment of MCS are not yet in place today.

Symptoms, Ailments & Signs

The multiple chemical intolerance manifests itself after exposure to the smallest amounts of volatile chemicals with many non-specific symptoms such as headaches , tiredness , lack of concentration , dizziness , shortness of breath , gastrointestinal problems , rheumatic complaints or unclear pains. The disease is also characterized by the fact that the symptoms increase over time. At the same time, the number of substances that cannot be tolerated is increasing.

However, a multiple intolerance to chemicals is clearly recognizable by specific characteristics. Thus, the symptoms only appear when there is chemical exposure. There is no sign of improvement. The complaints always arise at low concentrations of the chemicals. If the causative agent is removed, the symptoms disappear immediately. The triggers are unrelated chemicals.

Several organs or organ systems are always involved in the course of the disease. The consequences for those affected are serious. They affect the quality of life, professional life and general performance of the patient. Worse still are the psychosocial consequences. Those affected feel stigmatized and marginalized because they are often not taken seriously by relatives, friends and doctors.

Diagnosis & disease progression

Due to the unclear causes for the multiple chemical intolerance, a clear diagnosis is difficult. So far, there are no examination methods that can clearly diagnose the disease. The diagnosis of MCS is made only on the basis of the external appearance and the definition of the syndrome. However, laboratory tests and imaging methods remain inconclusive because no organic changes can be found.


This chemical intolerance can lead to various complaints. As a rule, however, these only occur if the person concerned comes into contact with the respective chemicals. If contact is avoided, no further complications or complaints arise.

The chemical intolerance leads to severe headaches or dizziness and severe tiredness. Disorders of concentration or coordination can also occur. Furthermore, many of those affected also suffer from shortness of breath or complaints in the area of ​​the stomach and intestines.

The patient’s quality of life is significantly reduced by chemical intolerance if contact with the chemical in question is not interrupted. The symptoms also increase over time if the disease is not treated. In the worst case, the person affected can also lose consciousness and possibly injure themselves in a fall.

Since there is no direct treatment for chemical intolerance, there are no particular complications. By avoiding the respective substance, the symptoms can be significantly alleviated. If the disease occurs due to psychological causes, psychological treatment is necessary to limit the symptoms.

When should you go to the doctor?

If the person affected experiences diffuse sudden changes in their health, they should check the environmental influences. If his breathing is exposed to gassing from chemicals, immediate action should be taken. In many cases it is sufficient to wear adequate respiratory protection and to spend a certain amount of time in an oxygen-rich environment. If after a few minutes there is already significant relief from the health problems, a doctor is often not needed. If you are free of symptoms after less than an hour, no further precautions need to be taken. If there is an increase in the existing symptoms or if an acute health-threatening condition develops, a doctor’s visit is necessary. In particularly serious cases, an emergency service must be alerted.

Tiredness, dizziness, coughing or concentration problems should be examined and treated. If there are disorders of the gastrointestinal tract, irregular concentration, dizziness and headaches, there is a need for action. In the case of rheumatic complaints, vomiting or nausea, a doctor’s visit is also advisable.

If the physical or mental performance decreases, mental abnormalities or peculiarities of the behavior appear, the person concerned needs help. Stomach pain, changes in food intake, loss of appetite, or irritability are other conditions that should be evaluated and treated. If the quality of life decreases, if there is a general feeling of unwellness or if the person concerned suffers from a feeling of illness, a visit to the doctor is advisable.

Treatment & Therapy

There is currently no causal therapy for the multiple intolerance to chemicals. In addition to avoiding the triggering chemicals, psychotherapeutic measures are now offered. However, many of those affected find this situation unsatisfactory. There are ways to exclude chemical vapors as far as possible.

The price, however, is often the complete isolation of the affected person from their social environment. This aspect in particular can even lead to an increase in the disease. Even psychotherapeutic treatment often cannot bring the desired success, because for many patients this is precisely where the problem lies. They find it discriminatory that the illness is supposed to be due to psychological causes.


It is difficult to prevent multiple chemical intolerance. The disease is multifactorial and is often triggered by a single exposure to chemicals. However, such an exposure can never be completely ruled out. Nevertheless, a healthy lifestyle can help reduce the likelihood of multiple chemical intolerance.

A healthy diet, plenty of exercise and avoiding smoking and drinking lead to a strengthening of the immune system and at the same time to greater resistance to stress. Avoiding contact with harmful substances and chemicals also reduces the risk of developing MCS.


Allergies require those affected to make a change in everyday life. Especially a multiple intolerance can be overwhelming at the beginning. Follow-up care is advisable to support the patient in the new situation. How long the follow-up treatment lasts depends on the extent of the chemical intolerance.

The affected person is looked after by an allergist. The goal is a largely unrestricted life despite intolerance to the respective chemicals. At the beginning, the specialist determines which chemical substances are not tolerated by the patient. The person concerned receives an overview of the allergens. He discusses with the doctor how he should take the intolerance into account in his everyday life.

In the case of multiple chemical intolerance, the procedure must be similar to that for food allergies. Cleaning agents containing allergens may no longer be used. Instead, the patient has to resort to harmless alternatives. Biodegradable household items are offered in the health food store.

If he worked in an environment where he was exposed to the chemicals prior to diagnosis, he should change roles within the company or consider retraining. In this case, in addition to medical care, career counseling at the employment office is also part of the aftercare.

You can do that yourself

A multiple intolerance to chemicals can be counteracted by those affected themselves. The most important measure is to avoid the relevant substances. People who have an allergic reaction to cigarette smoke or exhaust fumes must take precautions to avoid exposure to these substances in the first place. It may be necessary to change your job or your place of residence. Adjustments must also be made in the apartment. For example, air filters must be installed and airtight windows built in to avoid environmental influences from the outside.

In severe cases, special respiratory masks must be worn. Since multiple chemical intolerance can be accompanied by various complaints, the quality of life is often restricted. It is important to improve the quality of life through hobbies and an adapted lifestyle.

If you continue to feel unwell or experience the typical feeling of constriction, it may be useful to visit a self-help group. In conversation with others, those affected learn how to deal with the intolerance better and receive valuable tips. At the same time, an allergist or an internist must diagnose the disease and suggest suitable therapy measures. Drug treatment of chemical intolerance is usually also possible.

Lisa Newlon
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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.