The staircase to the girls' dormitory in Gryffindor is enchanted to become smooth when a boy is trying to climb it.

He was on the sixth stair when it happened. There was a loud, wailing, klaxonlike sound and the steps melted together to make a long, smooth stone slide. There was a brief moment when Ron tried to keep running, arms working madly like windmills, then he toppled over backward and shot down the newly created slide, coming to rest on his back at Harry’s feet. “Er — I don’t think we’re allowed in the girls’ dormitories,” said Harry

If a boy were to take a polyjuice potion of a girl, would they be able to pass the staircase? If there is no concrete evidence pointing to one way or the other, is there at least any references as to whether the polyjuice potion can fool enchantments or spells similar to this?

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    It can't fool the gringotts thing.
    – ibid
    Commented Nov 7, 2017 at 8:41
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    Polyjuice potion doesn't work on the Marauder's Map either. In chapter The Egg and the Eye (Book 4), the Marauder's Map identifies Barty Crouch Jr posing as Mad-Eye Moody. Commented Nov 7, 2017 at 10:00
  • Haha.. Awesome Question.
    – user931
    Commented Nov 7, 2017 at 16:52
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    The Thieves Downfall in Gringotts doesn't detect: it washes away concealment. The Marauder's Map does detect on a deeper level, but appears to be the only artifact capable of doing so (and is the only example I can recall of something not being fooled by polyjuice). Given how useful it would be to detect the true nature of someone polyjuiced (Azkaban, battle of 7 Potters, house common rooms, Gringotts, ministry of magic, interviews for Hogwarts employment, that time the DE needed Malfoy to visually identify Harry as Harry), it wouldn't be unreasonable to assume that such magic isn't common.
    – Mwr247
    Commented Nov 7, 2017 at 17:10
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    I expect the way the map works is an enchantment that literally grabs a person's name; the polyjuice potion is for changing physical form, I doubt it has anything to do with a person's name. It's likely that instead of the potion being unable to "fool" the map, they simply are manipulating and checking separate things. Commented Nov 7, 2017 at 17:13

2 Answers 2


We don't know for sure, but it would probably work

We never see it tested, and we don't know what enchantments the stairs use for detection (although whatever it is, we can reasonably assume it triggers the Glisseo charm). But there are a few observations we can make.

The stairs seem more interested in what you are than who you are. While the magical capability to determine one's "true self" certainly exists (such as those employed by the Marauder's Map), it seems like it would be overkill for the stairs to have an enchantment that thorough and specific, especially when you consider that there are other ways around such a simple deterrent for the truly determined (brooms, levitation, etc).

This can be corroborated by the fact that the majority of Hogwarts' protective enchantments are equally naive. Why would the common rooms or headmaster's office use simplistic passwords when they could use more reliable/secure identity enchantments? A basic enchantment to check for male/female seems to be the most likely implementation, for which polyjuice is sufficient enough to fool.

  • I like this answer more than the other one because I don't think the date matters as much as the intention behind the staircase enchantment, as touched upon in this answer. I will probably be accepting this one, but I will leave more time for any additional answers. Commented Nov 7, 2017 at 21:38

Probably not, but it may work, I think it would depend on the date of invention of Polyjuice. A good number of magical relics like the Marauders' Map are not fooled by the Polyjuice transformation but those are all items that post-date the invention of Polyjuice Potion; the castle, and thus its defenses and enchantments, is old so if the creators didn't take such a possibility into account, because "of course you can't do that with magic, we would know", then you might get away with it.

  • How do we know when the Polyjuice Potion was invented? Commented Nov 7, 2017 at 13:27
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    @TheDarkLord We don't, like I said it probably doesn't work, but it might if the stairs magic is limited by their date of installation.
    – Ash
    Commented Nov 7, 2017 at 13:32
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    I would think that Hogwarts keeps up-to-date with its security measures, so it shouldn't matter if Polyjuice came after the stairs were installed. Unless it was the day of and the Headmaster hadn't gotten around to updating that particular charm yet. Commented Nov 7, 2017 at 19:05
  • @DCOPTimDowd None of the gendered bathrooms are stated as having protective enchantments of this sort. This seems like less of a security thing and more of a last minute addition by the founders for a little extra "peace of mind", so highly doubt it would have been upgraded, assuming it even has the capacity to detect polyjuice in the first place.
    – Mwr247
    Commented Nov 7, 2017 at 22:26

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