Secretion vs. Excretion – What’s the Difference?

When you need to take a bathroom break, are you secreting materials from your body, or excreting them?

These questions can be confusing, especially for the non-biologists among us (who would often rather not think about such things). In reality, both secretion and excretion refer to substances created through normal body functions. Both are necessary for survival, and healthy bodies do both of them continuously or at regular intervals.

Still, you would look uninformed or amateurish if you were writing a paper for science class and used the wrong word, so it is important to know what each term means.

What’s the Difference Between Secretion and Excretion?

In this post, I will compare secretion vs. excretion. I will use each of these words in at least one example sentence, so you can see how they appear in context.

Plus, I will show you a memory tool that you can use to help remember whether something is an excretion or secretion.

When to Use Secretion

secretion versus excretionWhat does secretion mean? Secretion is a noun. In its biological sense, it refers to the release of a substance through normal body functions. The human body produces many secretions: mucus membranes secrete mucus, sweat glands secrete sweat, and glands in the skin secrete oil that protects and waterproofs skin.

For example,

  • Drinking plenty of water aids in the secretion of sweat, as well as keeping you well-hydrated.
  • When your nose dries out, membranes inside it produce a mucus secretion that traps germs and protects the delicate tissues beneath it.
  • Widely popular heartburn medications that block the secretion of acid into the stomach are associated with higher rates of chronic kidney disease, according to a new study by Johns Hopkins University researchers released Monday. –The Washington Post

Secretion is related to the verb secrete, which means to release a biological substance. Interestingly, the adjective secretive does not have a biological meaning, but instead means prone to keeping secrets or withholding information.

When to Use Excretion

definition of secretion definition of excretion definitionWhat does excretion mean? Excretion is also a noun. It refers to expelling waste products from the body via biological functions, or the waste products themselves.

Here are some example sentences,

  • Regular excretion can be a sign of healthy bowel functioning in humans.
  • Some animals gain information about richness of nutrients in an environment by examining the excretions of other animals.
  • After all, if you drink a cup of water and then immediately excrete half that amount in your urine, you haven’t added eight ounces to your water supply, but only four. –The New York Times

Excretion is related to the verb excrete, which means to expel waste products from the body. The adjective version of this word would be excretive.

Trick to Remember the Difference

define secretion define excretion Both of these words refer to the production of biological substances by the body. The main difference is that the products of excretion are waste, like feces or urine. The products of secretion perform other functions for the body, like lubrication, protection, or cleaning.

Secretion vs. Excretion Check: Another way to think of waste products might be as extra materials that the body can’t use anymore. Since extra and excretion begin with the same letters, it should be fairly easy to remember that excretion refers to expelling waste substances from the body.


Is it secretion or excretion? Secretion and excretion each refer to the production of substances by organs or tissues in the body.

  • Secretion refers to the production of many substances that the body uses, like sweat, oil, and mucus.
  • Excretion only refers to expelling waste from the body.