Never mix Sodium hypochlorite (chlorine bleach) with Ammonia
Toxic gas
Chloramine gases are released. These are severe respiratory irritants: exposure causes coughing, shortness of breath, chest pain, wheezing, nausea, watery eyes and irritation of the throat, nose and eyes, and in serious cases pneumonia and fluid in the lungs. In an enclosed space such as a bathroom, concentrations build quickly. Get into fresh air at once and seek medical advice. FEELING BETTER SHORTLY AFTERWARDS IS NOT AN ALL-CLEAR: the regulator recommends medical observation for 24 to 48 hours after overexposure, because fluid on the lungs can be delayed.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Keep away from children and pets
- Consider professional help
How this happens
Sodium hypochlorite reacts with ammonia to form chloramines, which are volatile and escape into the air as gas. The reaction requires no heating and no unusual conditions. It is the everyday circumstances that make this dangerous: ammonia is present in some glass and multi-surface cleaners without being prominent on the label, and it is present in urine, so the reaction commonly happens when bleach is used on a toilet, a litter tray or a pet accident rather than when somebody deliberately combines two bottles.
CleaningHQ describes what kind of reaction this is and what it does to a person. It does not publish concentrations, quantities or conditions, because a warning specific enough to be followed is not a warning.
If it has already happened
Get everyone into fresh air straight away, and do not go back inside to open windows. Anyone with breathing difficulty, chest pain, persistent coughing, or a chemical splash to the eyes needs medical attention — treat it as an emergency and call your local emergency number. In the United Kingdom, use NHS 111 or 999 as appropriate; clinicians can consult the National Poisons Information Service.
The substances involved
- Sodium hypochlorite (chlorine bleach) — A powerful oxidising bleach and disinfectant. It is also the substance behind the most common serious household chemical accidents, and must never be mixed with anything.
- Ammonia — An alkaline cleaner found in some glass and general-purpose products. Recorded here principally because of what it does when mixed with bleach.
Evidence
Strongly supported
Among the most consistently documented domestic chemical hazards. Sprint 2 replaced the unread occupational reference that was carrying this alone with two state health departments whose pages were read in full, and both state the hazard and its effects directly. The practical warning is stated in terms of PRODUCTS rather than named chemicals because the common accidents involve people who did not know ammonia was present. Sprint 27 re-read the substance sheet and added the delayed-onset observation window, which is the only line in this register that tells a reader what to do AFTER an exposure they believe they have got away with.
Sources
Dangers of Mixing Bleach with Cleaners
Washington State Department of Health · Government or regulator
Relied on for: That mixing bleach with ammonia produces toxic chloramine gases, and the specific health effects listed including pneumonia and fluid in the lungs. (states this directly)
Verification: a person has read the passage relied on.
Read on — The whole page: the bleach-and-ammonia section and the bleach-and-acid section. Supports the claim as stated.
Hazard Alert — Worker Health and Safety: Mixing Bleach with Other Cleaning Products Can Be Deadly
New Jersey Department of Health, Environmental and Occupational Health Surveillance Program · Government or regulator
Relied on for: That mixing bleach with ammonia creates chloramine gases with the effects described, and that ammonia-containing products are among those not to be combined with bleach. (states this directly)
Verification: a person has read the passage relied on.
Read on — Page 1, the two case reports and the bleach/ammonia and bleach/acid paragraphs; page 2, the "DANGEROUS CHEMICAL COMBINATIONS — DO NOT MIX" list and the safe-work-practices panel. Supports a wider statement — our claim was widened. The register gained authoritative support for three hazards CleaningHQ had not recorded: bleach with alcohols, hydrogen peroxide with acetic acid, and the sequential-use route evidenced by both case reports. Incompatibility records were added for the first two, and the sequential-exposure wording on the existing bleach-and-acid record now rests on a case report rather than on inference.
NIOSH Pocket Guide to Chemical Hazards
US National Institute for Occupational Safety and Health (NIOSH), CDC · Poison or chemical-safety authority
Relied on for: That chloramine and chlorine are recognised hazardous respiratory irritants with established occupational exposure limits. (background and mechanism only)
Verification: the work exists and is described correctly. Nobody has yet read the specific passage.
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That medical observation is recommended for 24 to 48 hours after overexposure to sodium hypochlorite, as pulmonary edema may be delayed. (states this directly)
Verification: a person has read the passage relied on.
Read on — Description and Use, Hazard Summary, Health Hazard Information, Handling and Storage, and the Emergency Responders reactivity panel on the back page. Re-read in full in Sprint 27. Supports a narrower statement — our claim was reduced. This does NOT establish that bleach damages a stainless steel sink or an aluminium pan in ordinary surface cleaning, and CleaningHQ does not model it as though it did. What it establishes is a CONTAINMENT AND STORAGE constraint — bleach should not be held in metal equipment or piping, because oxygen release can rupture the container. The domestic pitting claim for stainless steel rests instead on the stainless trade association's guidance about prolonged soaking, a separate fact from a separate source, and the two are deliberately not merged.
Last reviewed by a person on .
Last reviewed by a person on .