Is gum numbing gel safe to swallow?

No it is not: Are you asking for use for a child or an adult? Either way, it not safe to swallow, and should not be used in young children, especially those under two years of age. Give infants a cold teething ring or dampened, frozen washcloth to chew on instead. For adults, any relief would be extremely temporary. see you dentist instead and have the problem properly diagnosed and treated instead.

Safe in small doses: it is safe. Dentists use them to relieve pain caused by dental injections and to prevent the gag reflex. However, FDA warns that prescription oral viscous lidocaine 2 percent solution should not be used to treat infants and children with teething pain. Hope it helps.

In small amounts: In small amounts and accidentally, yes. In large amounts, no.