Does swallowing skin peeled from the lips or inside the mouth, whether intentionally or unintentionally, or in the form of small particles, affect the validity of the fast?

The fast is invalidated by intentionally swallowing anything that peels off the outer skin of the lips, even if it is a small amount. The same applies to anything inside the mouth if it is possible to distinguish it and avoid it. However, if it is impossible to distinguish it, the fast is not invalidated, because it is considered like food remnants mixed with saliva. As for swallowing out of forgetfulness, it does not invalidate the fast, according to the preponderant opinion.