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Never mix

Bleach + Drain cleaner

Chlorine gas (with acid drain cleaners)

Don't mix bleach with drain cleaners. Acid drain cleaners, including those containing sulfuric or hydrochloric acid, can release chlorine gas when mixed with bleach. [1] [2] [3]

If you already mixed

Leave the area right away and get to fresh air. For household cleaners, open windows and doors to let in fresh air, and stay away until the gas has gone away. [4] [5]

Call 911 for any trouble breathing or swallowing. [4]

Eyes: rinse with lots of room-temperature running water for at least 15 to 20 minutes. [6]

Remove contaminated clothing; wash skin with soap and water. [7] [8] [4]

For mild symptoms or questions, call Poison Help 1-800-222-1222. [4]

A fading smell is not an all-clear: the smell may not be noticeable to people exposed many times, and chlorine gas is heavier than air, so it may linger near the ground. [8]

Chlorine gas can be released when bleach is mixed with acid drain cleaners. [1] [2] [3]

Poison Control says many drain cleaners contain concentrated acids (such as sulfuric or hydrochloric acid) or alkalis (such as sodium or potassium hydroxide). [9]

Chemicals

Sources

  1. Canadian Centre for Occupational Health and Safety (CCOHS) — Cleaning Products - Working Safely retrieved 2026-10-27
  2. Washington State Department of Health — Dangers of Mixing Bleach with Cleaners retrieved 2026-10-27
  3. New Jersey Department of Health — Hazard Alert: Mixing Bleach with Other Cleaning Products Can Be Deadly retrieved 2026-10-27
  4. Washington Poison Center — Chloramine Gas retrieved 2026-10-27
  5. Centers for Disease Control and Prevention — Chlorine fact sheet retrieved 2026-10-27
  6. National Capital Poison Center (Poison Control) — Help for poisons splashed in the eye retrieved 2026-10-27
  7. NJ Department of Health — Hazardous Substance Fact Sheet: Sodium Hypochlorite retrieved 2026-10-27
  8. National Capital Poison Center (Poison Control) — Chlorine gas retrieved 2026-10-27
  9. National Capital Poison Center (Poison Control) — What's in drain cleaner and what happens if you drink it? retrieved 2026-10-27