Why Do I Smell Onions Everywhere?

A dry mouth allows bacteria to thrive. Bacteria that live in the mouth can make compounds that have sulfur. These compounds are especially stinky. They can smell like rotten eggs or onion, for example.

Why do I smell onions when there are none?

An olfactory hallucination (phantosmia) makes you detect smells that aren't really present in your environment. The odors detected in phantosmia vary from person to person and may be foul or pleasant. They can occur in one or both nostrils. The phantom smell may seem to always be present or it may come and go.

Why do I keep smelling onion and garlic?

Onions and garlic are members of the allium family. They're similar in composition and contain many of the same sulfur compounds. Sulfur compounds give foods their distinctive flavor. They also release distinctive gasses when cut or mashed and mingle with gas-emitting bacteria, causing scented breath.