How to reheat leftovers safely
Safe reheating depends on how food was stored first, the guidance for your country and heating it thoroughly before eating.
Start with safe storage
Reheating is not a reset button. A casserole that was cooled and refrigerated promptly is different from one that stood on the kitchen counter for an unknown period. Check the storage history before deciding how to heat it, and follow the packet instructions where they apply.
For example, a portion of refrigerated chilli can be heated for dinner; a takeaway that was left warm for hours may need a different answer. The checker asks about the details it supports rather than assuming every leftover has the same history.
England, Wales and Northern Ireland
Food Standards Agency guidance says cooked leftovers may be eaten cold when they were cooked properly, cooled and refrigerated promptly. If you reheat them, heat until steaming hot throughout and do not reheat the same food more than once.
Microwaves can leave cool areas. Stir or turn food where that makes sense, allow it to stand if the instructions say so, and split a large portion into smaller portions when that helps the middle heat evenly. These are practical ways to check the whole portion, not an alternative to heating it thoroughly.
Scotland
Food Standards Scotland likewise says reheated food should be steaming hot all the way through and should not be reheated more than once. Its cooking guidance also says to follow label instructions and take particular care that a large dish is heated through in more than one place.
Keep the nation-specific wording in mind. Safe to Eat? routes Scotland to Food Standards Scotland sources and England, Wales and Northern Ireland to Food Standards Agency sources; it does not treat one authority’s wording as guidance for the other.
United States federal guidance
US federal guidance uses a temperature-based approach for the supported leftover situations: USDA commonly advises reheating leftovers to 165°F / 73.9°C, checked with a food thermometer. That is different from simply copying the UK “reheat once” wording into a US answer.
For microwave reheating, arrange or stir food so heat can reach the middle and avoid cold spots. USDA guidance says a slow cooker should not be used to reheat cold leftovers; reheat them by another method first, then use the slow cooker to keep them hot if appropriate.
Hob, oven and microwave
On the hob, heat and stir a sauce, soup or curry so it is hot throughout. In an oven, use an oven-safe dish and make sure the centre—not only the browned edges—is properly reheated. In a microwave, a small covered portion can be easier to heat evenly than one deep container.
The UK checker uses a steaming-hot-throughout question for its supported paths. The US checker asks about the 165°F / 73.9°C thermometer confirmation and method. If the food was not refrigerated properly, stop and check that issue first rather than relying on reheating alone.
Can leftovers be eaten cold?
UK FSA guidance allows properly cooked, promptly cooled and refrigerated leftovers to be eaten cold. That does not make every cold leftover suitable: the storage history, use-by date, food type and packet directions still matter. If in doubt, do not use this page to override a label instruction.
US users should also consider the prior cold storage and handling. The country-specific checker is a better next step when you know the food, time and temperature details.
What about rice?
Rice needs separate attention because reheating cannot correct unsafe cooling or storage. Food Standards Scotland says not to keep rice for more than 24 hours and only to reheat it once. For takeaway rice, FSS notes that the earlier handling may be unknown, so it may be safer not to reheat when you cannot establish how it was prepared and stored.
See the rice left out guide for UK cooling context, or use the checker for a supported rice question.
When the checker cannot confirm safely
It cannot fill in missing handling history, judge an unmeasured US internal temperature, or make a food safe after a known unsafe period. A “cannot confirm safely” result is not a claim that food is definitely unsafe; it means the verified rule set cannot support a confident answer from the facts provided.
Official sources used
United Kingdom
Food Standards Agency: Cooking your food Food Standards Scotland: Cooking food
United States
USDA FSIS: Reheating leftover take-out food USDA FSIS: Reheating leftovers in a slow cooker
Related guidance
Read about leftovers in the fridge, defrosting food safely and food left out after refrigeration.
Use the checker for your situation
This page gives general UK and US guidance. Check your food for the situations Safe to Eat? currently covers.
Sources and scope
Page reviewed: 16 September 2026. UK and US source sets are displayed separately above; this is a page review date, not a single source-pack freshness date.
This resource is based on UK and US food-safety guidance and does not replace the checker’s personalised questions. Read how the checker works and see the official sources.