Intended use is the broad general purpose of the device; indications for use is the specific disease, condition, or population it's cleared for.
Intended use decides whether FDA regulates the product at all and shapes the whole regulatory strategy. Indications for use is the narrower, submission-specific statement filed on Form 3881 that defines exactly what you can claim in labeling and marketing once cleared. A device can have one intended use but multiple indications for use across different submissions — expanding indications later usually means a new 510(k), even if the underlying device hasn't changed.
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