Short answer: Black or gray spots on a bathroom ceiling are usually mold growing on moisture from showers. The EPA says that when mold keeps returning in a bathroom, you need more ventilation (run the exhaust fan or open a window) and more frequent cleaning. Small areas under about 10 square feet can usually be cleaned with detergent and water. If the spots are brown rings, sag or sit under a toilet or tub upstairs, suspect a leak instead.
Quick diagnosis
| What you notice | Most likely cause | What to check | Call a pro? |
|---|---|---|---|
| Dark spots over the shower area | Steam condensing on the ceiling | Run fan during and after showers | No |
| Mold returns weeks after cleaning | Weak or missing exhaust fan | Test fan with a tissue | If it does not pull |
| Brown ring stain, not spots | Leak from above (pipe, toilet or roof) | See water stain on ceiling | Often |
| Ceiling soft, bubbling or sagging | Water trapped above | Do not push on it | Yes |
| Mold patch larger than about 10 sq ft | Long-term moisture | Leave it; get help | Yes |
Clean small areas
- Fix any leak first.
- Wear gloves and eye protection and ventilate the room.
- Scrub with detergent and water, then dry completely (EPA).
- Do not paint over mold. Once the surface is clean and dry, a mildew-resistant bathroom paint can help.
- Never mix bleach with ammonia or other cleaners.
Stop it coming back
- Run the exhaust fan during showers and for about 20 minutes after.
- Check that the fan actually pulls air: a tissue held to the grille should stick.
- Keep the door open after showers and squeegee walls.
- Keep indoor humidity below 60%, ideally 30% to 50% (EPA).
If it is a leak
A brown stain with defined edges, or spots right under an upstairs toilet or tub, means water from above. Our guide to a water stain on the ceiling explains how to find the source.
When to call a professional
- Mold covers more than about 10 square feet.
- The ceiling is soft, sagging or stained from a leak.
- The exhaust fan does not work or vents into the attic instead of outside.
- Someone in the home has asthma, allergies or a weakened immune system.
What it usually costs
Small cleanups cost only supplies. HomeGuide (2026) lists fixing a leak and replacing damaged ceiling drywall at about $500 to $2,500.
Frequently asked questions
Why does mold keep coming back on my bathroom ceiling?
The moisture source is still there: usually poor ventilation after showers. Cleaning alone does not fix it.
Should I use bleach on bathroom ceiling mold?
The EPA does not recommend bleach as routine cleanup. Detergent and water work for small areas; never mix bleach with ammonia.
Related problems
Sources
- U.S. EPA: A brief guide to mold, moisture and your home
- U.S. EPA: Mold cleanup in your home
- HomeGuide: Ceiling repair cost (2026)
This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.