Although this question seems a bit gross, are blood and saliva compatible with Polyjuice Potion? As far as I recalled, only hairs are compatible.
The Polyjuice Potion, which is a complex and time-consuming concoction, is best left to highly skilled witches and wizards. It enables the consumer to assume the physical appearance of another person, as long as they have first procured part of that individual's body to add to the brew (this may be anything - toenail clippings, dandruff or worse - but it is most usual to use hair). The idea that a witch or wizard might make evil use of parts of the body is an ancient one, and exists in the folklore and superstitions of many cultures.
Blood and saliva certainly are body parts.
It depends on if they’d be considered “a bit of the person”.
The recipe for Polyjuice Potion requires a bit of the person that the potion is being used to turn into, but it’s never specified that it has to be a hair.
“Oooh, look, powdered horn of a Bicorn – don’t know where we’re going to get that … Shredded skin of a Boomslang – that’ll be tricky, too – and of course a bit of whoever we want to change into.”
- Harry Potter and the Chamber of Secrets, Chapter 10 (The Rogue Bludger)
However, the times we see Polyjuice Potion being used, it’s always a hair that’s added, never any other part. It’s not quite clear if that’s because hair is preferable, or because it’s less “icky” and easier to obtain than something like toenails.
Blood would probably work, it’s been used in other potions, but saliva never has.
While we never see anyone use blood in Polyjuice Potion, the Dark Lord does use the blood of his enemy in the potion to restore his body. This proves that at least some potions can use blood.
While it doesn’t rule it out, there’s no potion that we know of that requires or can use saliva as an ingredient.