Is it safe to put formula in a warm car?
No. Hot temperatures break down nutrients in formula and dramatically accelerate chemical leaching from plastic containers and bottles. Prepared formula left in a hot car should be discarded.
What's actually in it
Baby formula stored or warmed in a hot car faces two problems. First, temperatures inside a closed car can reach 60C or higher on a warm day. At these temperatures, plastic formula containers and bottles leach chemicals at dramatically higher rates than at room temperature. Second, heat degrades heat-sensitive vitamins and the bioactive components in formula.
Plastic baby bottles left in a hot car with formula inside are among the highest-risk scenarios for combined chemical migration and nutrition degradation in infant feeding.
What the research says
Studies on plastic migration at elevated temperatures consistently find exponential increases in chemical migration above 40C. A 2026 study on plastic bottle chemical migration found that temperature is the primary driver of increased bisphenol and antimony migration from PET plastic into beverages.
For hot-weather situations, keep formula in an insulated cooler bag if you need to transport it. Prepare and use formula within 2 hours at room temperature, or discard. Never use formula that's been sitting in a hot car. Use glass bottles to eliminate plastic chemical migration from the bottle itself.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Chemical migration from plastic water and baby bottles | Food Chem Toxicol | 2026 |
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