"Black mould" is a common name for the dark mould that grows on damp walls, window frames and sealant. You may read online that black mould is "toxic" in a way other mould isn't. The government's guidance on the health risks of damp and mould doesn't sort mould by colour or species. It treats damp and mould of any kind as a health risk to be dealt with, by fixing the cause.
This article is general information, not medical advice. If you're worried about your health or someone else's, speak to a GP or call NHS 111. In an emergency, call 999.
How damp and mould can affect health
According to the government's guidance, living with damp and mould can cause:
- breathing problems such as cough, wheeze and shortness of breath
- a higher risk of airway infections, including aspergillosis
- new or worse allergic conditions, such as rhinitis and asthma
- eye irritation, including allergic conjunctivitis
- eczema and itchy skin or rashes
- poor mental health, from living in unpleasant conditions and worrying about physical health
In 2019, damp and mould in English homes was estimated to be associated with about 5,000 cases of asthma and about 8,500 lower respiratory infections.
In December 2020, two-year-old Awaab Ishak died from a severe respiratory infection caused by prolonged exposure to damp and mould in his home. The guidance was written in response to the coroner's concerns after his inquest.
Who is most at risk
The guidance lists people who are more likely to be seriously affected:
- people with health conditions such as asthma, COPD or cystic fibrosis
- people with weakened immune systems
- pregnant women and new mothers
- babies, children and young people
- older people
- people who are bedbound, housebound or have mobility problems
What to do
- Deal with the moisture. Mould comes back if the cause isn't fixed. See what causes mould.
- Clean small patches carefully, wearing a mask, gloves and goggles, with a mould and mildew product rather than bleach. If you're in one of the higher-risk groups, it's sensible to ask someone else to do it. See cleaning small areas yourself.
- Get larger areas removed professionally.
- If you rent, report it to your landlord in writing. See who has to fix damp and mould in a rented home.
- If anyone has symptoms that could be linked to damp and mould, tell your GP about the conditions at home.
What you don't need
You don't normally need a laboratory test to find out which species of mould you have before dealing with it. The priority is finding and fixing the moisture. See mould testing and damp surveys for when testing can help.
Sources
- Understanding and addressing the health risks of damp and mould in the home, GOV.UK, updated 1 April 2026