Why Is Hippopotamus Sweat Red?

Hippos might appear to sweat blood, but the truth is far less grisly. A hippopotamus doesn't actually perspire in the same way that humans do. Instead, it secretes a substance made up of a red pigment called hipposudoric acid and an orange pigment called norhipposudoric acid. Both secretions protect the hippo's skin from the sun. Hipposudoric acid also functions as an antibiotic.

More about hippos:

• A hippo pregnancy lasts about eight months, and births usually take place during the rainy season.


• The antibiotic properties of hippopotamus sweat are important to the health and survival of hippos. They often live in contaminated water and typically are covered with scratches and sores that result from frequent clashes with other hippos. Hipposudoric acid helps prevent these wounds from becoming infected.


• Hippos like to graze at night and, on average, eat 88 pounds (40 kg) of vegetation each day.

Frequently Asked Questions

What causes the red coloration in hippopotamus sweat?

The red coloration in hippopotamus sweat is due to two unique pigments, hipposudoric acid and norhipposudoric acid. These pigments act as natural sunscreens and have antibacterial properties, protecting the hippo's skin from the sun's harsh rays and preventing infections in aquatic environments where hippos spend much of their time.

Is the red sweat of hippos actually blood?

No, the red sweat of hippos is not blood. It's a common misconception due to the color, but the secretion is purely a combination of the pigments mentioned earlier. These pigments are specific to hippos and are not found in the blood or sweat of other animals.

Does the red sweat of hippos serve any purpose besides sun protection?

Yes, besides acting as a sunscreen, the red sweat of hippos also serves as an antiseptic. The acidic nature of the pigments provides a protective layer against pathogens, which is particularly useful since hippos often sustain injuries while in close quarters with each other or moving through rough terrain.

How do hippos produce their red sweat?

Hippos produce their red sweat through specialized glands in their skin. Unlike humans, whose sweat glands are designed for thermoregulation, hippo sweat glands secrete the red pigmented molecules that spread over their skin, providing the necessary protection from the environment.

Can the red sweat of hippos stain their surroundings?

While the red sweat may temporarily color the water they bathe in or the surfaces they rub against, it does not cause permanent staining. The pigments are water-soluble and can wash away with rain or in larger bodies of water where hippos reside.

Are there any other animals that produce colored sweat like hippos?

Colored sweat is quite rare in the animal kingdom, making hippos unique with their red sweat. Most other animals either do not sweat at all or produce clear sweat. The hippopotamus's red sweat is a distinctive adaptation that has not been observed in other wildlife.