According to the official Tervis website, it's generally not recommended to put their cups in the microwave. But, why is that? It's because the microwave can cause the insulation to break down, which can lead to a loss of its magical temperature-keeping powers.
Now, we know what you're thinking - what if I just need to heat up my coffee for a few seconds? Will it really cause any harm? The answer is, it's not worth the risk. Microwaves can be unpredictable, and you don't want to end up with a damaged cup or, worse, a scalding hot mess on your hands.
