Many previous clients have reported seeing mushroom growth in their bathrooms. This can sometimes be jutting out of baseboards, or next to the shower from incidental spillage, and sometimes even be growing out of the base of the toilet.
When mushrooms are present in a bathroom, this usually indicates a wider moisture issue. Here are some examples:
Mushrooms growing out from under the baseboard: this can sometimes indicate an active leak within the wall cavity, and there could then be considerable mold growth within the cavity since the water profile was high enough that mushrooms have developed.
Mushrooms growing out from under the toilet: this can indicate a toilet leak, which could be from a broken wax ring. If mushrooms are growing, then moisture could have entered the surrounding tile/carpet which could need inspecting to deduce further information for mold concerns.
Mushrooms growing from caulking: this is rare, but if it's occurring, can indicate ineffective caulking whereby moisture is getting in behind the caulking and creating moisture buildup.
If mushrooms are present within your bathroom, it is wise to call a mold inspector or water damage specialist to further assess the area to address the area before it potentially gets any worse. Don't ignore it!
MOLD HEALTH EFFECTS BLOG AND RESEARCH