Only if labelled microwave safe
Most paper cups are lined with plastic or wax so they hold liquid. Unless the cup is marked microwave safe, treat it as a one trip container.
A paper cup looks harmless, but the lining does the work. A polyethylene lining softens at high heat, and a wax lining melts. Cups made for hot coffee are designed to hold hot liquid, not to be heated in a microwave, and the glue and seam can fail.
| Short answer | Only if labelled microwave safe |
|---|---|
| Lining | Plastic or wax, both of which can soften or melt |
| Risk | Leaks, hot spots and a weakened cup |
| Safe choice | A ceramic or glass mug |
| Check | The base of the cup or the packaging |
How to reheat a drink from a paper cup
- Pour the drink into a microwave safe ceramic or glass mug.
- Heat in short bursts of 20 to 30 seconds and stir between them.
- Leave it for a few seconds before drinking, because liquid can be hotter than it looks.
- Never reheat in a lidded or sealed cup.
- Throw the cup away afterwards rather than reusing it.
What happens when you get it wrong
- Leaks. The seam softens and the cup gives way while you are holding it.
- Burns. A weakened cup with hot liquid can spill suddenly.
- Taste and chemicals. Heating a lined cup can release a taste of wax or plastic.
Use this instead
A ceramic mug, which handles repeated heating.
A glass measuring jug for larger amounts.
Frequently asked questions
Are paper cups microwave safe?
Only the ones marked as such. Most are not designed for it.
Can you microwave a paper coffee cup with a lid?
No. The lid traps steam, and the cup can burst or spill.
Can you microwave wax paper cups?
No. Wax melts at microwave temperatures.
What about paper bowls?
The same applies. See the paper plates page for the rules.