I stayed at a friend’s old apartment for a few days and soon noticed strange bumps on my skin. “I noticed these weird bumps appearing on my skin shortly after,” and at first they seemed harmless. I assumed they were mosquito bites or a mild allergy, but the situation didn’t quite fit that explanation.

What made it worrying was the pattern. “They seemed to show up overnight, sometimes in small clusters,” and the itching made them hard to ignore. Since nothing else had changed in my routine, the cause didn’t seem to be food, soap, or clothing.

Because of that, attention turned to the apartment itself. “It quickly became clear that something in the environment might be causing the reaction.” Older or rarely used places can hide many irritants that only become obvious after spending the night there.

Many people experience similar skin reactions in old apartments. These reactions are often linked to insects like bed bugs or fleas, or to environmental triggers such as dust mites, mold spores, or chemical residue trapped in carpets and furniture.

Insects are especially suspicious because they usually bite exposed skin during sleep, which explains why bumps appear by morning. Older buildings can also contain allergens that “trigger skin reactions in people who are sensitive,” making overnight stays uncomfortable and sometimes alarming.