brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

Examples of brain fog in a Sentence

Recent Examples on the Web

To help protect cognitive function and prevent brain fog, experts recommend including enough omega-3 fatty acids and antioxidants in your diet while keeping tabs on your vitamin B12, vitamin D, and iron levels. — Tom Gavin, EverydayHealth.com, 2 Nov. 2026

Research is emerging in areas like menopause and brain health, which may draw interest from patients concerned about related muscle loss, brain fog, and mood changes. — Team Verywell Health, Verywell Health, 2 Nov. 2026

For instance, fatigue, brain fog and body aches can be linked to menopause, fibromyalgia or even an underlying thyroid disorder. — Cheyenne Buckingham, Washington Post, 24 Oct. 2026

But many live with fatigue, weakness, brain fog and other symptoms for months or years before a deficiency is caught. — Amanda Schupak, CNN Money, 23 Oct. 2026

Word History

First Known Use

1853, in the meaning defined above

Rhymes for brain fog

• agog
• backlog
• bulldog
• bullfrog
• eclogue
• eggnog
• groundhog
• hedgehog
• leapfrog
• prolog
• sheepdog
• watchdog

Medical Definition

brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

This brain fog can be a result of being overly stressed, tired, carrying extra weight, consuming too many calories or consistently consuming a diet poor in nutrients.

—Kylie Helgens, The Gazette (Cedar Rapids, Iowa)