Women finds mysterious yellow stains in her house, hunts for an answer, and fails to erase them. Then they appear in her car: ‘I found the culprit’

A Reddit post on the popular r/CleaningTips subreddit has left the internet trying to solve a homeowner’s bizarre “mysterious yellow stain” problem. The poster said bright yellow marks had started appearing around the house, seemingly without any obvious explanation.

What started as a single smudge eventually turned into a much bigger mystery. The yellow marks reportedly showed up on carpets, a cleaning towel, a foam shoe, a toothbrush charger, the bathroom sink and even a bathroom cabinet. The post quickly drew more than 7,000 upvotes as Reddit users tried to figure out what could possibly be leaving the same strange stain on so many different surfaces.

The variety of objects involved only made the mystery harder to solve. The stains weren’t confined to one room or one type of material, leaving commenters to consider everything from cleaning products and mold to pollen and other environmental causes.

Everyone had a unique theory

The homeowner described the bright yellow color as so unusual that they felt like they were “going crazy.” Naturally, Reddit had plenty of theories.

One commenter said they had experienced something similar and eventually discovered that their husband’s turmeric pills were responsible.

“This happened to me and it turned out to be my husband’s turmeric pills, one had split open in the bottle so every time he took one a little bit of turmeric would be on his hands and then end up somewhere else,” the user wrote.

Others suggested everything from pollen and mildew to mineral deposits and aerosol cleaning products.

“Do you have a lily plant in your garden? The yellow pollen from them easily tracks on clothing and also transfers easily to other objects,” another commenter asked.

Another had a completely different theory.

“Do you have tomato plants by chance? I looked like I lost a fight with a yellow highlighter after pruning a tomato plant. It took body scrub to get it off my skin. I can imagine it would not be easy to get out of fabrics,” the commenter wrote.

For a while, turmeric seemed like one of the more convincing possibilities. Turmeric contains curcumin, a naturally occurring compound known for its intense yellow color and ability to stain surfaces. If turmeric powder or oil gets onto a floor, clothing or footwear, it can potentially be carried from one surface to another without being immediately noticed.

But the homeowner eventually returned with an update that appeared to solve the mystery — and turmeric wasn’t the culprit after all.

It was a half opened AZO packet

“I think i found the culprit! I found a half opened AZO packet in the bathroom cabinet. Notably, the packet was missing 1 pill. I hadn’t noticed this because I had it in a little container on the shelf. Other items in the container had a yellow stain on it so I think it’s safe to say that this is how bathroom cabinet, counter and charger became stained,” she wrote.

Mysterious yellow stain showing up all over house and making me feel crazy! 😩
by u/Mental_Investigator3 in CleaningTips

The discovery would explain at least some of the stains in the bathroom, particularly those on the cabinet, counter and toothbrush charger. It also gave the internet a satisfying answer to a mystery that had attracted thousands of theories.

The lesson, apparently, is that sometimes the strangest cleaning mystery has a surprisingly ordinary explanation. And sometimes Reddit will spend thousands of comments investigating turmeric, pollen and tomato plants before someone checks the bathroom cabinet.