Do some frogs have poison in their skin?
Yes. Frogs (and toads) have mucous glands all over their skin to
help keep their skin lubricated. If frogs do not keep their skin
moist they will dry out and die. In some species, such as the
poison dart frogs, the secretions from these glands are highly
toxic. All frogs and toads have a degree of these poisons, even if
it is only in retrace amounts, but in some species the
concentration of toxins is much greater, providing an effective
defence mechanism.
The mucous glands in frogs' and toads' skin is different from
the parotid glands which some species of toads have just behind
their eyes, which contain irritants and other toxins to deter
predators.