I don't think there is a canonical answer to this but I guess it could be deducted from the attributes of werewolfs and the way the potion works.

Let's say he uses his own hair for the potion. Or perhaps a hair of another human, does not really matter. I can imagine two possible scenarios. If he uses it right before the full moon, does the potion prevent the werewolf transformation? If it does prevent it, does he retain human form but goes insane anyway since the potion does not change the mentality of the person, only physical form? What if he would manage to drink it righ after the transformation, does he turn back to human?

As per answer to this question: As Part Veela, Why Could Fleur Delacour Use Polyjuice Potion to Transform into Harry, and Why Could Hagrid Not? it seems to me that both cases are legit, altho I am not so sure about the second one - transforming an "animal" to a human.

  • 1
    His head would explode and there would be a big mess
    – Valorum
    Commented Feb 5, 2018 at 21:37

2 Answers 2


Does the potion prevent the werewolf transformation?

There's no explicit canon answer, but we can infer that the answer is nearly 100% certain to be "no". If it worked that way, werewolves wouldn't have any problems, Lupin wouldn't have to be isolated in the shack when he was a student; and there wouldn't have been any need for wolfsbane potion.

Same goes for drinking it after transformation.

  • Good point here, as Rogue gives a potion to Lupin in order to help him not suffer the transformation, it seems rather likely that if it was possible, he would have done it.
    – Tloz
    Commented Aug 31, 2015 at 11:27
  • maybe he didn't think of it, or he couldn't, polyjuice was hard to make
    – user84093
    Commented Feb 6, 2018 at 7:57

Polyjuice only lasts for one hour (in its normal recipe). A werewolf would need much more than one hour to prevent the transformation completely.

That being said, the werewolf curse is probably present in the hair of a werewolf, and they would simply transform anyway (wasting a month and the ingredients for Polyjuice Potion.

Source: Chamber of Secrets (USA pg 213, para 9). Hermione says

Once we've drunk it, we'll have exactly an hour before we change back.


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