Why evaporation doesn't create danger here
While alcohol does slowly evaporate from vanilla extract, the tiny amount your cat ingested (a teaspoon spread over hours) wouldn't concentrate enough to reach toxic levels. Even if half the liquid evaporated, the remaining alcohol would still be diluted across the entire teaspoon's original volume. Cats process alcohol poorly, but this exposure stays below the threshold for acute poisoning.
The bigger concern is how your senior cat's metabolism handles even small amounts. Older livers work slower, so watch for prolonged effects like unsteady movements or excessive drowsiness over the next 8 hours. These would indicate her system is struggling more than expected with the alcohol.
What to watch for in the next day
Focus on changes in her usual patterns - does she stumble when jumping down from furniture, or sleep through meals she'd normally wake for? Senior cats often show subtle signs like squinting more or hesitating before jumps. Compare her current behavior to how she acted yesterday, not just textbook symptoms.
Check her water intake too - alcohol can cause mild dehydration that hits older cats harder. If she visits the bowl more often or has unusually sticky gums, offer diluted chicken broth to encourage drinking. The sugar content isn't a major concern from one exposure, but wipe her face to prevent skin irritation from sticky residue.
Why this differs from fresh vanilla extract
Overnight exposure to air does change vanilla extract, but not in ways that increase toxicity. The alcohol that evaporates first is the same compound that causes intoxication, leaving behind more of the vanillin and sugar. Your cat licked a milder version than if she'd found a freshly opened bottle.
The real risk of leaving vanilla uncovered isn't concentration - it's attracting pests. Ants or flies could contaminate the bottle, creating future hazards. Store baking extracts in sealed cabinets, not countertops, especially with curious older cats who might investigate smells more persistently than kittens.
When to call the vet about lingering effects
Most cats show any alcohol-related symptoms within 4-6 hours, but seniors may process it slower. If she still seems off the next morning - refusing breakfast, hiding more than usual, or having trouble with litter box steps - that warrants a checkup. Describe exactly when she licked it and what changes you've noticed.
Emergency care is only needed if she develops tremors, can't stand up, or stops responding to you. For mild wobbliness, keep her in a quiet, carpeted room with water and a low-sided litter box until it passes. Block access to stairs or high perches where she could fall while unsteady.
The full verdict, portion guidance and serving notes are collected on the Vanilla extract food facts page.