Can you still eat shiitake mushrooms when they've grown larger?

Under normal circumstances, enlarged shiitake mushrooms are safe to eat as long as there are no abnormalities. However, if swelling is caused by spoilage, they should not be consumed. If in doubt, it's recommended to carefully observe their condition before deciding. Detailed analysis is as follows:

Enlargement of shiitake mushrooms is usually due to inherent varietal characteristics or sufficient moisture and high maturity during growth. These mushrooms have plump, firm flesh, no off-odors, uniform color, and show no signs of mold or stickiness. They are nutritious and safe to consume, with no adverse health effects, and may even have a more tender and flavorful texture.

If the mushroom enlargement is accompanied by abnormal signs—such as soft, sticky flesh, dull coloration, or a sour, rotten, or moldy smell—it indicates microbial growth and spoilage. Spoiled shiitake mushrooms may produce harmful substances that can cause gastrointestinal discomfort, including stomach pain and diarrhea after consumption. In such cases, they must not be eaten.

When purchasing shiitake mushrooms, choose ones that are uniformly sized and firm in texture. Store them in a cool, well-ventilated area or refrigerate them, avoiding moisture exposure. Always inspect mushrooms for signs of spoilage before cooking; discard immediately if any abnormalities are found.