Quite simply, why do some farts feel warmer than others? Some feel regular, while others feel like lava. What causes this?

If there is no real temperature difference, why do I perceive some to be warmer than others? Does this contribute to the smell? I've notice the hotter they feel, the worse they smell usually.

  • $\begingroup$ Burning sensation in the anus might also be related to decreased nerve function due to various causes including diabetes and vitamin b deficiency $\endgroup$
    – One Face
    Commented Oct 19, 2018 at 6:25
  • $\begingroup$ a better question why would you think they would not? $\endgroup$
    – John
    Commented Feb 15, 2023 at 20:48

1 Answer 1


Fundamentally, the smell of what comes out will depend on what goes in - primarily a function of what you ate and conditions in your gut (including the mix of bacteria).

In addition, if you ate something containing large amounts of capsaicin (the chemical that makes chili peppers spicy), it's going to "burn" on the way out. Aside from flatulence, overconsumption of capsaicin can irritate the intestines and cause diarrhea.

  • $\begingroup$ So you're saying the temperature fluctuates depending on the food you eat? Does capsaicin affect temperature? $\endgroup$
    – heez
    Commented Oct 19, 2018 at 14:53
  • 3
    $\begingroup$ Capsaicin definitely affects the perception of temperature, but may cause localized irritation which in turn can raise actual (thermometer) temperature. Heat production is generally the product of metabolism; if something with large amounts of available energy ends up in the small intestine with sufficient bacteria to process it, expect tons of hot and obnoxious gas. If you're eating something that didn't have much of any energy in the first place, then there's nothing for the bacteria to metabolize in the first place. $\endgroup$ Commented Oct 19, 2018 at 15:06
  • 1
    $\begingroup$ I think the OP is asking about temperature in terms of the actual gas feeling warmer vs a burning sensation from capsaicin $\endgroup$ Commented May 22, 2022 at 11:42

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