Paris Hilton is firing back at folks online who are poking fun at the size of her baby boy's noggin ... saying there's absolutely nothing wrong with him.

Mama P shared some snaps Friday holding Phoenix ... while she got some love from her followers, she also heard from lots of trolls -- with jokes flooding the comment section about Phoenix's head.

Play video content LEAVE PHOENIX ALONE

People have taken to TikTok to point out all the rude things being said ... and Paris responded to one of the people defending her, writing, " 🥺😢There are some sick people in this world.☹️My angel is perfectly healthy."

She went on to say, "And yes, of course he has been to a doctor, he just has a large brain."

As we reported, Paris announced at the beginning of the year she had Phoenix with her husband, Carter Reum ... and she's been sharing some pretty adorable shots of her new bundle of joy while navigating motherhood for the first time.

Play video content PARIS CLAPS BACK

We chatted with her about being a mom in March, and she said she's loving it -- and, more importantly, she ain't ready to stop at just one kid!

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