Quick answer: Mould can and does cause health problems — respiratory symptoms, worsening asthma, allergic reactions and, for immunocompromised individuals, serious fungal infections. The people most at risk are infants, elderly people, those with asthma or respiratory conditions, people with weakened immune systems, and pregnant women. If symptoms are worse at home and better when away, the home environment is likely a contributing factor — see your GP and document the connection in your medical records.
If you or someone in your household has been experiencing health symptoms — persistent coughing, difficulty breathing, skin irritation, worsening asthma — and you also have mould in your home, the connection is a reasonable one to investigate. Mould can and does cause health problems, and for some people the effects are serious. This guide explains what we know about the health effects of mould exposure, who is most at risk, what symptoms to watch for, and what to do.
This guide is not a substitute for medical advice. If you are concerned about your health or the health of someone in your household, speak to your GP.
How does mould affect health?
Mould produces spores — microscopic particles that the mould releases to reproduce. These spores are airborne and, when breathed in, can cause a range of health effects depending on the type of mould, the concentration of spores, the duration of exposure, and the individual's sensitivity.
The main health effects associated with indoor mould exposure are:
- Respiratory symptoms — persistent coughing, wheezing, shortness of breath, nasal congestion and throat irritation
- Worsening of existing conditions — asthma attacks triggered or worsened by mould spore inhalation; hay fever symptoms worsened outside of pollen season
- Allergic reactions — sneezing, runny nose, red eyes and skin rashes in people sensitised to mould spores
- Hypersensitivity pneumonitis — a more serious inflammatory lung condition triggered by repeated exposure to mould spores in susceptible individuals; symptoms include fever, chills, muscle aches and breathlessness
- Fungal infections — rare in people with healthy immune systems but a serious risk for immunocompromised individuals; Aspergillus species found in building environments can cause aspergillosis, a potentially serious lung infection, in people with weakened immunity
The most serious case in the UK in recent years was that of Awaab Ishak, a two-year-old boy who died in 2020 following prolonged exposure to mould in a social housing property in Rochdale. The coroner found that his death was caused by a respiratory condition triggered by mould. This case led directly to Awaab's Law, which requires social landlords in England to act on mould reports within legally defined timeframes.
Who is most at risk?
Some people are significantly more vulnerable to the health effects of mould than others:
- Infants and young children — their developing respiratory systems are more susceptible to damage from mould spore inhalation
- Elderly people — reduced respiratory reserve and immune function increase susceptibility
- People with asthma — mould spores are a well-established asthma trigger; exposure in the home can significantly worsen asthma control
- People with allergies — particularly those with existing respiratory allergies
- People with weakened immune systems — whether from illness, medication or medical treatment; the risk of serious fungal infection is substantially higher in this group
- Pregnant women — the health effects of mould exposure during pregnancy are not fully characterised but respiratory symptoms in pregnancy carry additional risk
If any of these apply to members of your household, mould in the home should be treated as a priority health issue, not a background problem to be managed later.
What symptoms might be connected to mould?
The following symptoms, particularly if they have appeared or worsened since you noticed mould in your home, may be connected to mould exposure:
- Persistent cough, particularly at night or in specific rooms
- Wheezing or breathlessness without a previous diagnosis
- Worsening asthma that is harder to control than usual
- Nasal congestion or runny nose that is worse indoors than outside
- Itchy, red or watering eyes
- Skin rashes or persistent itching
- Fatigue or headaches that improve when away from home
- Repeated respiratory infections
The pattern of symptoms — worse at home, better when away — is one of the clearest indicators that the home environment is a contributing factor.
What the law says
If you rent in England: under the Homes (Fitness for Human Habitation) Act 2018 and Awaab's Law for social housing tenants, your landlord is legally required to address mould that presents a risk to health. Health symptoms connected to mould are directly relevant to the legal standard — a property where occupants are experiencing mould-related health effects is not fit for human habitation.
If you rent in Wales: the Renting Homes (Wales) Act 2016 applies and creates a continuous fitness standard across all rented accommodation.
What you should do now
See your GP. Describe your symptoms and tell them about the mould in your home. Ask for the potential connection to be documented in your medical records. This documentation is important if you need to escalate your housing complaint or pursue legal action against your landlord.
Report the mould to your landlord in writing if you rent. Reference the health symptoms being experienced by members of your household. Keep copies of everything.
Reduce exposure in the short term. Keep the most affected rooms as well-ventilated as possible. Do not dry brush or scrub mould without a mask — this releases spores into the air at high concentration.
Address the mould safely. For surface mould, use a biocidal product with adequate dwell time, and wear FFP2 or FFP3 disposable mask, rubber gloves and eye protection when cleaning. For larger areas of mould or where strip-out is needed, this is work for a contractor using H-Class extraction — the correct standard for biological agent containment during mould remediation.
When to seek urgent help
- Seek immediate medical attention if anyone in the household experiences severe breathlessness, chest pain or high fever that may be connected to mould exposure
- If you are immunocompromised and have been exposed to significant mould, speak to your specialist or GP promptly — the risk of fungal infection is a serious consideration
- Contact environmental health at your local council if your landlord is not acting and health symptoms are worsening
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