It is difficult to ascertain what the persistent blood clot on the lip may be due to without a photo. However, conditions such as:
- Angiomas
- Haemangioma
- Port wine stains
Can all contribute to a red area that is persistent and have little symptoms. In more serious cases, even skin cancers can present as a pink or red spot that is persistent and grows over time.
It is best to seek medical advice early if you have a new, persistent, or changing skin lesion. Hope this helps.