← Back
Nutrition and daily life

Leftovers and reheating: store well, reheat fully

Leftovers save time and money, but stored badly they let bacteria multiply fast. Some bacteria (such as Bacillus cereus in rice) make toxins that survive heating. This section covers the rules for leftovers.

Last updated: ~1 min read
Small containers in the fridge.
Figure 1.Sealed containers — Leftovers and reheating: store well, reheat fully

01Short answer

Refrigerate cooked food within 2 hours; split large pots into small containers so they cool quickly. Eat leftovers within 1–2 days (shorter is safer during treatment). Reheat only once and until steaming, at least 74 °C; stir halfway through in a microwave. Cool rice especially quickly and eat it within 1 day. Do not leave food out at room temperature once taken from the fridge. Do not taste doubtful leftovers; throw them out.

02Simple explanation

In the fridge within 2 hours.

1–2 days.

Once, until steaming.

Rice: extra care.

03Scientific explanation

Bacillus cereus grows in cooked rice left at room temperature and makes a toxin that reheating does not destroy.

WHO: foodborne illness is more severe in people with weakened immunity; the five keys are keep clean, separate, cook thoroughly, keep food at safe temperatures, and use safe water and raw materials.

04What happens in the body?

Freezing

Leftovers can be frozen in portions; thaw in the fridge and reheat fully.

Reheated hot food — Leftovers and reheating: store well, reheat fully
Figure 2.Steaming stew — Leftovers and reheating: store well, reheat fully

Restaurant leftovers

Refrigerate them within 2 hours and eat them the next day.

An old container by the bin.
Figure 3.Old leftovers — Leftovers and reheating: store well, reheat fully

Neutropenia

When neutrophils are low, even ordinary germs can cause serious infection, which is why the rules are stricter.

General rules

This section is part of the general food-safety rules in “Handwashing: the simplest protection” and “Eggs and dairy: safe choices” and “Food safety: four simple rules”.

05Safety: four steps

Check, swap the risky, prepare properly, use in time.

Check — Date and condition.1CheckDate and condition.
Swap — A safe choice.2SwapA safe choice.
Prepare — Clean and thorough.3PrepareClean and thorough.
In time — No delay.4In timeNo delay.
CleanHands and surfaces.
CookGerms die.
ColdGrowth slows.

06Key points at a glance

TopicIn brief
FreezingLeftovers can be frozen in portions; thaw in the fridge and reheat fully.
Restaurant leftoversRefrigerate them within 2 hours and eat them the next day.
NeutropeniaWhen neutrophils are low, even ordinary germs can cause serious infection, which is why the rules are stricter.
General rulesThis section is part of the general food-safety rules in “Handwashing: the simplest protection” and “Eggs and dairy: safe choices” and “Food safety: four simple rules”.

07Key terms

Bacillus cereus
A bacterium that can be found in rice.
Reheating
Heating food again.
Foodborne infection
An infection spread through food or water.
Neutropenia
Low neutrophils.

08Key points

  • Cool quickly.
  • Eat soon.
  • Reheat fully.
  • When in doubt, throw it out.
  • Call if you have a fever.

09Frequently asked questions

Can I reheat more than once?

No; reheat only the portion you will eat, once.

Can I eat leftovers cold?

During treatment reheating is safer.

Are these rules for ever?

No. They are usually relaxed as blood counts recover; your team will say.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Can I reheat more than once?

  2. Can I eat leftovers cold?

  3. Are these rules for ever?

My questions

12Sources

  1. World Health Organization. Five Keys to Safer Food manual
  2. World Health Organization. Food safety fact sheet
  3. U.S. Food and Drug Administration. Safe Food Handling
  4. National Cancer Institute. Eating Hints: Before, During, and After Cancer Treatment
  5. American Cancer Society. Cancer-related Fatigue
  6. American Cancer Society. Physical Activity and the Person with Cancer
  7. Cancer.Net (ASCO). Fatigue
  8. World Health Organization (WHO). Physical activity — fact sheet
  9. U.S. Food and Drug Administration (FDA). Food Safety for Older Adults and People with Cancer, Diabetes, HIV/AIDS, Organ Transplants, and Autoimmune Diseases
  10. U.S. Food and Drug Administration. Antibacterial Soap? You Can Skip It
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
Last updated: ← Back to the list

Open the interactive site →