Multiple Chemical Sensitivity: Symptoms, Causes, Diagnosis, and Treatment

Katie Rapkoch, CHPC

Published on

May 13, 2024

Updated on

February 9, 2024

Medically reviewed by

Ben Ahrens, HHP

Multiple Chemical Sensitivity, commonly referred to as MCS, is a chronic medical condition in which patients experience symptoms triggered by exposure to low levels of chemicals in their immediate environment. People might experience any number of symptoms when they are exposed to scented products, plastics, smoke, paints, or even pesticides. MCS can even be caused by food sensitivity![1] Some patients discuss how they experience nausea, fatigue, and headaches.

At its foundation, MCS is a limbic system condition that occurs because of neurological trauma. In other words, upon exposure to any chemical, vital, environmental, or psychological threat, the limbic system will respond in a unique way. Every individual experiences this situation differently and it is important to recognize that your symptoms might not be the same as someone else’s. Multiple Chemical Sensitivity has also been commonly referred to as:

  • Environmental Illness
  • Sick Building Syndrome
  • Idiopathic Environmental Intolerance
  • Toxicant-induced Loss of Tolerance
  • Chemical Sensitivity 20th Century Syndrome
  • Toxic Injury

If you feel that you might be experiencing this syndrome, you are not alone. Every day, there are thousands of individuals who suffer from MCS and experience a range of symptoms.

Symptoms of Multiple Chemical Sensitivity

It is important to recognize that symptoms arise from a variety of different sources.  It is not only the low-level toxicity of the substance around the individual, but also potentially psychological factors that also might extend the effects of the symptoms.  In general, the symptoms do vary from person to person[2], but the main symptoms are:

  • Headaches
  • Rashes
  • Asthma
  • Muscle and joint aches
  • Fatigue
  • Memory loss
  • Confusion

If you experience one or more of these symptoms, it could be a sign that you might be experiencing MCS.  Despite some of the symptoms being clear in association with exposure to chemicals and toxins, there is still controversy over how to distinguish MCS from other conditions. It is important that you do your research and talk to medical professionals, but often individuals can tell if they potentially have MCS based on their environment and the presence of their symptoms in certain situations. If you are in an environment with others and still experience the same symptoms, it can be an indicator that you might have MCS or symptoms of the disorder.

Take the MCS Self-Assessment

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How often do you find yourself:

Having distorted sense of smell or taste?*


Very Rarely





Causes and Risk Factors of Multiple Chemical Sensitivity

With MCS, it is hard to recognize the specific causes of the condition, but it is almost always related to a traumatic event that took place surrounding a toxin or a substance within the individual’s immediate environment. Often, it might not even be one specific interaction with the substance, but it could be the accumulation of interactions within a toxic environment.

However, the trauma or the traumatic event causes the patient to get stuck within a neurological loop that causes a subconscious self-defensive response to the presence of a toxin or substance. No matter if it is one event or multiple exposure events, this is often the cause of people’s MCS.

The risk factors for MCS are simple to recognize, because they involve the individual’s immediate surroundings. If you are stuck in an environment where there are toxins or substances that potentially cause allergies for you, then you are likely at risk of developing this if your limbic system responds with hyperactivity instead of being able to recognize that you are not in immediate danger. MCS will only form when you have prolonged heightened stress combined with acute exposure. In other words, the more time you spend in an environment with these toxins or allergens, the more likely you are to develop MCS symptoms.

Unfortunately, this is not a conscious process and it takes the repeated training of the brain to trigger and eventually sustain these new conditions and these expectations. The limbic system will continue to respond to the substances and then learn that they are dangerous, even if they are not significantly present. This leads to further symptoms and your neurological processes will acquire the expectations rather than develop them instantly. This all happened through conditioning, and it all depends on the exposure you have to the substance. The less exposure you have to toxic environments and substances, the less likely you are to potentially experience the symptoms of MCS.

Additionally, there are studies that show that any sort of trauma can be a causation of MCS. This includes emotional or physical trauma, even something remotely unrelated. The brain can become traumatized , because in these situations, the brain is suffering abuse because of the broken feedback loop within MCS. These events in someone’s life can further make their risk of developing MCS higher, but a diagnosis is not the end for you.

How Multiple Chemical Sensitivity is Diagnosed

To this day, it is still difficult to diagnose MCS. Many people claim that it is controversial to diagnose due to the fact that the condition shares several different symptoms with that of other physical health concerns.

In the general sense, if the individual suffers from ill health when exposed to chemicals in concentrations that normally do not affect others, then this is grounds for medical professionals seeking to find out if the individual is suffering from MCS. From there, medical professionals would assess the symptoms[3] and then determine if the individual does in fact suffer from MCS, and not something unrelated to the condition.

One of the main instances that this would be a viable example would be if the patient is very sick, even when they are exposed to very low levels of the toxin in their environment. In some cases, the severity of MCS can merit filing for disability as a response for their situation. It should be noted that this is extremely rare, but a possibility with cases that have progressed without treatment.

How Multiple Chemical Sensitivity is Treated

There are various treatments that individuals will seek to help relieve their symptoms of MCS and eventually rid themselves of the condition entirely. However, not all treatments are created equally[4].

Prescription Medication

Many individuals might not deem this to be an appropriate first choice, but it can help get chemical levels in order if nothing else has worked thus far. This should be deemed a last resort because it often disrupts the natural functionality of the patient’s limbic system.


Involving a brain wave study, patients will be taught how to concentrate, breathe, and control their reactions in their system. It works for some, but not for all, and it can come at a cost.

Talk therapy

For individuals who need to get their feelings out, cognitive behavior therapy is a viable option. This helps individuals understand their thoughts, rework their behavioral patterns and understand for themselves where they might be struggling more than they should be. This can be helpful, but it also takes some time and therapists are often not as affordable as other options.

Targeted amino acid and nutritional therapies

Since MCS is an issue with the limbic system, this can be incredibly helpful for supplementing what is needed to repair the feedback loop. This can help keep the levels of your 5HTP, L-tyrosine, GABA, phosphatidylserine, and others at an adequate level for healing.

Qi Gong or Tai Chi

These ancient Chinese activities are known for their ability to help people calm their breathing through physical movement. These can truly calm the limbic system and gradually help to rebalance it. However, it can be hard to know exactly what you are doing without consulting an expert.

Reiki practitioner, acupuncturist, or therapeutic massage practitioner

These are great for individuals looking for programming to help rework their body in a new and unique way, but these again can be more expensive than individuals might be able to spend for their treatment, or they might not have the resources available to them in their community.

How We Approach MCS

At re-origin, we focus on finding the error in the feedback loop that you are experiencing in your limbic system. We believe that reworking your feedback loops and addressing the overactive threat-response system, is the key to your healing and finding permanent relief from your MCS symptoms.

The re-training of the feedback loop is relatively easy to understand, especially given the exposure and the causations of MCS. MCS is related to the feedback loop that the individual develops since they were first introduced to that toxic substance. The first cause of a response from the limbic system is when the substance is detected. It doesn’t matter if it was first detected then, or if you find yourself encountering the same toxin from a prior experience. Either way, the brain will recognize that the substance is not desired. From this, there will be a stress response in the form of chemical interactions within the brain.

From there, this is how individuals will experience their symptoms in the form of headaches, nausea, or other concerns. What causes this is the hyperactivity of inflammatory cytokines, T-cells, B-cells, and other symptomatic responses. This puts the limbic system into overdrive and forces the body to refuse to rest and heal, which is necessary for the immune system function over time. Without this crucial rest period, the body ends up in a vulnerable state.

Then, peak discomfort occurs and the individual begins to worry. This is often when the individual recognizes their coping mechanism, employs it (however consciously or subconsciously), and seeks momentary relief. However, the worry is not gone forever, and the individual gets stuck in this loop, becoming more and more sensitized to the substances that their brain first recognized as toxic to their body. This severely compromises the immune system, the brain, and the health and well-being of the individual.

In order to rework your limbic system, we understand the importance of finding healthy patterns for your central nervous system and your limbic system again. In many MCS patients we have seen, there are challenges to their immune, autonomic, and their endocrine systems[5] as a result of their condition. We work to help them reestablish healthy feedback loops and get back on the right track by re-training their limbic system through our proprietary and science-based neuroplasticity exercises.

In your new feedback loop after experiencing neuroplasticity training, your brain will recognize that the toxin is not dangerous and that your body can handle the challenge. After all, this is a neurological condition, not psychological! You will be willing to let your body take over, which relieves you of the inflammation and the coping response. You will be desensitized and train your limbic system to relax, heal, and take care of your body, instead of becoming hyperactive in the face of low-level toxins.

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How to Live and Cope with Multiple Chemical Sensitivity

At re-origin, we believe that no one should ever have to live with MCS. We understand the struggles that you face and the experience that you have with this unique condition. We believe in overcoming your condition through gradual exposure. We always go at your speed and recognize your comfort level, but encourage you to be courageous and work to challenge your mind, body, and your limbic system. Through incremental training, you can begin to see your symptoms dissipate and your responses change to the environments that previously caused you pain.

The key is to systematically perform these exercises in order to adhere to the methodology. Repetition is the name of our success with our patients and we believe that this is how many of our patients work to overcome MCS and fail to see it return in their lives. As long as you repeat and return to your training with re-origin, you will see a difference, and be on your path to wellness once again. You don’t have to live with MCS, and we are excited to help you on your journey to restoring your health and your peace of mind.

A Final Word from re-origin

MCS is a condition that is controversial in its diagnosis, but a very real condition that people experience in their everyday lives. No matter how it happened, it involves a very simple feedback loop that our team of expert neuroscientists and psychologists of the re-origin Brain TrustTM have studied to help you to repair. With our proprietary neuroplasticity training, we can teach and support you to address and undo the underlying cause of the condition, relieve your own symptoms, lessen the occurrence of MCS, and regain the peace of mind that you once had. No one should have to live with MCS. Check out our neuroplasticity training program to regain your peace, recover your limbic system, and return to living your best life.


  1. National Research Council (US). Multiple Chemical Sensitivities: A Workshop. Washington (DC): National Academies Press (US); 1992. Possible Mechanisms for Multiple Chemical Sensitivity: The Limbic System and Others. Available from:
  3. National Research Council (US). Multiple Chemical Sensitivities: A Workshop. Washington (DC): National Academies Press (US); 1992. Diagnostic Markers of Multiple Chemical Sensitivity. Available from:
  5. National Research Council (US). Multiple Chemical Sensitivities: A Workshop. Washington (DC): National Academies Press (US); 1992. Neuropsychiatric & Biopsychosocial Mechanisms in Multiple Chemical Sensitivity: An Olfactory-Limbic System Model. Available from:


What does MCS stand for?
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MCS stands for Multiple Chemical Sensitivity, which relates to individuals who experience abnormal responses to low-level toxins in their environment.

What is Multiple Chemical Sensitivity Disorder?
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This is the condition that is caused by a toxin or substance that produces physical symptoms such as nausea, headaches, and muscle aches. This condition is unique because the individual is exposed to low-level toxins and gets caught in a limbic system feedback loop that causes them psychological and physical stress as a result of their exposure. This is a disruption that requires treatment to help remedy the patient’s current health.

Is MCS a disability?
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For most individuals who are diagnosed with and experience MCS, it is nothing more than a condition that requires treatment to help rework the limbic system loop. However, in severe cases, it can be claimed as a disorder, but this requires medical attention and diagnosis to discuss how serious the situation is for the individual.

How do you recover from MCS?
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Recovery is only a short path away. There are numerous treatment options that you can take, but the best would be to retrain your brain to help repair the feedback loop that is causing your symptoms. re-origin has a neuroplasticity program to help you regain your health and your peace back while healing your limbic system from the symptoms of MCS.


Katie Rapkoch, CHPC