What Is Formaldehyde Poisoning?

  • Sara NakanishiMaster’s of Science - Genes, Drugs, and Stem Cells - Novel Therapies, Imperial College London
  • Catrin EllisBachelor's degree, Chemistry, University of York, UK
  • Amaan SiddiqueBsc (Hons), Biomedical Science,University of Surrey, UK


Formaldehyde is a chemical compound found in many manufacturing processes and is a by-product of vehicle emissions and cigarette smoke. It is reportedly among the 25 most produced chemicals in the world.1 This colourless gas is rapidly absorbed through inhalation and in the gastrointestinal tract, which can cause skin and mucous irritation. Many chemicals are classified by their danger to health and the environment, allowing proper regulations to be put in place by the government. Since 2016, the aqueous form of formaldehyde, formalin, was classified as a Category 1B carcinogen, a substance that can cause cancer.2 It is also classified as a corrosive agent, something that is capable of damaging another through contact. 

This chemical has many synonyms. Look out for:

  • Formalin (the aqueous solution of formaldehyde)
  • Formic aldehyde
  • Methanal
  • Methyl aldehyde
  • Methylene oxide
  • Oxomethane
  • Paraform

What are the characteristics of formaldehyde?

Formaldehyde is a colourless gas at room temperature, which is highly toxic and flammable. Compared to other dangerous gases, formaldehyde has a pungent, irritating smell that can be detected even at small levels.

This chemical is classified as corrosive, flammable, and carcinogenic. While this compound can be dangerous, if used safely, with the proper protective measures, there should be no harm to the health of the person handling it. It is only when safety measures are not followed or dangerous situations are encountered that there is a health risk.

Sources of formaldehyde exposure

Occupational exposure (industries, laboratories)

Depending on the type of formaldehyde, this chemical can be multi-functional and used in many industries:

  • Wood products
  • Paper
  • Synthetic fibres
  • Plastics and coatings, such as varnishes and lacquers
  • Textiles, such as clothing and carpets
  • Insulation
  • Adhesives
  • Cleaning and detergent agents
  • Embalming
  • Veterinary disinfection and fumigation

Formaldehyde resins are used to manufacture several resins. They are used as an adhesive or binder in fabric, plastics and textiles.

Formaldehyde-urea is used for insulation during construction.

Environmental sources (cigarette smoke, vehicle emissions)

Formaldehyde is not only a chemical found in manufacturing processes; it can also be found in nature. Some natural sources of this compound are found during the decomposition of organic materials, such as methane,  forest fires, and volcanic activity.3

  • Industrial emissions
  • Vehicle exhaust
  • Cigarette smoke
  • Incense burning

When does it become dangerous?

Formaldehyde can be found in our environment and homes, so how much is too much and when does it become dangerous? The Public Health of England reports that in the atmosphere, formaldehyde is usually below 0.01mg/m3 but can reach up to 0.02mg/m3 in industrial areas. Indoors have been reported to have higher levels. This is due to the age, temperature, season, and/or air exchange rate of your home and can be attributed to things such as burning incense, smoking, and cooking. At peak times, when your home is new or during humid times of the year, formaldehyde concentrations can reach up to 0.2mg/m3.

Mechanism of formaldehyde poisoning

Most of the time, exposure to formaldehyde occurs through inhalation of the gas or by skin and/or eye contact. This gas is easily absorbed into the lungs, making it dangerous. Most people can be alerted to a leak of formaldehyde gas by its pungent, irritating smell, which is present even in small doses. However, some individuals are more sensitive to this gas, experiencing symptoms before they can detect it. 

Symptoms of formaldehyde poisoning

Acute exposure symptoms

Acute exposure symptoms are short-term symptoms that can be treated fairly quickly.

  • Respiratory irritation (coughing, wheezing)
  • Eye and mucous membrane irritation

Formaldehyde contact with the eyes or skin can cause irritation in varying degrees depending on the amount of formaldehyde. In the eye, it can cause water at concentrations of 61.5mg/m3. If in contact with high concentrations of formaldehyde, there is a high risk of vision loss or scarring of the cornea (corneal opacification).1

  • Skin reactions (burning, rash)

On the skin, formaldehyde solutions of 1-2% can cause skin irritation. At higher concentrations, there is the potential for blisters and fissures.

Formaldehyde should never be consumed. If ingested, there is a severe risk of injury to the gastrointestinal tract and potential death. Once ingested, symptoms can include nausea, diarrhoea, abdominal pain, ulceration, and vomiting.

Chronic exposure symptoms

Chronic or prolonged exposure to formaldehyde can create symptoms and conditions that require prolonged, potentially lifelong, treatment. Classified as a cancer-causing chemical by the International Agency for Research on Cancer, there is evidence of nasal tumours and leukaemia in those exposed over an extended period, such as years of working within an industrial plant.

Chronic exposure can also lead to neurological issues. Some symptoms reported are mood changes, irritability, headaches, attention deficit, impaired memory and dexterity. Repeated exposure to formaldehyde can cause the person to be more likely to develop respiratory issues such as asthma or bronchitis.1 They can also have an allergic skin reaction called dermatitis when coming in contact with it.

Treatment and management

It is important to remove yourself from the source of exposure during accidental exposure to formaldehyde. The next step is to seek medical advice if you have ingested or inhaled formaldehyde. 

If you have a formaldehyde solution spilling on your clothing and skin, it is important to immediately remove the soiled clothing, but make sure not to pull the clothing over your head, as this will cause you to inhale or expose the eyes to the solution. Following this, you should rinse and wash the area with lukewarm water for at least 10-15 minutes. After this, you should seek medical advice.

In the case of exposure to the eyes, first remove contacts if applicable, then rinse with lukewarm water for at least 10-15 minutes. After this, seek medical advice.

There is no medication specific for treating formaldehyde poisoning. Those affected will be monitored by medical professionals, and supportive therapy will be given depending on the symptoms.4 Those with skin lacerations will be treated as burns, and medication can be administered.

Some ways to reduce formaldehyde in your home include:5

  • Allow products to ventilate to reduce gas levels: In products produced with formaldehyde, when sealed in packaging, the gas remains with the product. You can reduce these levels by removing the packaging outside and letting the product air out before bringing it into your home. 
  • Ventilate your home: increase airflow in your home by opening windows, using fans, or a central ventilation system. This will bring fresh air into your home, lowering the concentration of formaldehyde.
  • Regulate heat and humidity: As previously stated, heat and humidity play a role in the amount of formaldehyde that stays in your home. You can keep your house cooler and less humid through air conditioning, opening windows, or having a dehumidifier.
  • Smoke outdoors

Regulatory guidelines and standards

Due to the high risk of formaldehyde poisoning, governments have standards and guidelines that create limits and classifications on formaldehyde exposure. These guidelines are referenced when exposure is identified to help people properly react and treat the patient. 

The government imposes regulations on the amount of chemicals a worker can be exposed to, called workplace exposure limits (WELs). In the UK, both the long-term and short-term WEL is 2.5mg/m3. 


Formaldehyde is a common, highly produced chemical used in many manufacturing processes and occurs in nature. It can be found in homes at low levels and varies depending on the age, temperature, season and humidity of the home. It is a colourless gas at room temperature with a pungent, irritating odour. It is classified as corrosive, flammable, and a category 1B carcinogenic. The most common exposure to formaldehyde is through inhalation and direct contact. These methods can cause airway irritation, coughing, crying, and an allergic skin reaction or burn. In repeated exposure, there is the possibility of developing asthma, nasal cancer, bronchitis, and impaired neurological symptoms. Digestion of a formaldehyde solution can cause severe irritation of the throat and stomach, leading to burns and, depending on the concentration of the solution, death. Governments have implemented safety guidelines that set limitations on the amount of formaldehyde workers and the public are allowed to be exposed to, as well as safety precautions to remain protected. This is to prevent any symptoms or long-term damage to those who work with formaldehyde. When exposed to this chemical, it is important to remove yourself from the source and seek medical advice. If a formaldehyde solution is spilt on you, remove the soiled clothing without pulling it over your head and rinse the affected skin with lukewarm water and soap before seeking medical advice.

This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Sara Nakanishi

Master’s of Science - Genes, Drugs, and Stem Cells - Novel Therapies, Imperial College London

Bachelor of Science - Biochemistry/Chemistry, University of California San Diego

Hello! My name is Sara and I have a diverse background in science, particularly in biochemistry and therapeutics. I am extremely passionate about heart health and mental illness. My goal is to break down complex scientific topics to share with those with non-scientific backgrounds so they can be well-informed about their conditions and ways to live a balanced life. I believe that education and awareness are key to leading a healthy lifestyle and I hope to inspire others through my writing.

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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