Is burns around lips or mouth an aid in determining whether not a victim has swallowed poison?

No, burns around the lips or mouth are not a reliable indicator of poison ingestion. While certain corrosive substances can cause burns to the delicate skin around the mouth or lips when ingested, many poisonous substances do not have this effect. Conversely, burns around the lips or mouth can also occur due to accidental contact with irritants or due to other unrelated medical conditions. Therefore, the presence or absence of burns around the lips or mouth cannot be used to conclusively determine whether or not a victim has swallowed poison.