Few people would argue that noting smells as foul as a decomposing body. During the human decomposition process, dozens of different types of gases are released. Eight of these gases primarily contribute to the horrible stench that oftentimes is called the “smell of death.” The primary odors that make up the stench associated with a decomposing body are:

  • Rotting fish
  • Feces
  • Mothballs
  • Rotten eggs
  • Rotten cabbage
  • Garlic

Primary Gases That Give Rise to the “Smell of Death”

Although dozens of different types of gases are released during the human decomposition process, there are eight gases that primarily contribute to the “smell of death,” the awful stench that surrounds a cadaver. These eight gases create the six distinctive odors associated with a decomposing body. These gases are:

  • Cadaverine
  • Putrescine
  • Skatole
  • Indole
  • Hydrogen sulfide
  • Methanethiol
  • Dimethyl disulfide
  • Dimethyl trisulfide


Together with putrescine, cadaverine is one of the two most dominate gases associated with the human decomposition process. A significant amount of cadaverine can be toxic. Although most commonly associated with the purification of animal cadavers, cadaverine is also found in very small quantities in living animals, including humans. Small amounts are found in human urine and semen. Cadaverine has a rotting fish odor.


As noted a moment ago, putrescine is one of the two most common gases associated with human decomposition. Extensive exposure to putrescine can be toxic. In addition to being associated with decomposing animals, putrescine can also be found associated with living animals in small amounts. For example, putrescine is found in small quantities in human semen and can be associated with the odor of the bad breath. Putrescine has a rotting fish odor.


Skatole is yet another foul-smelling gas associated with the decomposition of human remains. Skatole is detectable during the human decomposition process because as remains decay, waste contained in the digestive system is released, a proves which includes the release of feces. Skatole has the odor of feces.


Indole is widely found in the environment. Indole gas is created as a result of the processes of bacteria.  During the human decomposition process, bacteria flood a body when their main repositories of intestines and pancreas after death. Billions of bacteria flood the body, resulting in the creation of a considerable amount of indole gas. Indole has the odor of mothballs.

Hydrogen Sulfide

Hydrogen sulfide is a flammable, potentially explosive, poisonous gas. It is produced when organic matter breaks down in the absence of oxygen, which is the case in the human decomposition process. This gas is also commonly present in swamps and sewers. Hydrogen sulfide has the odor of rotting eggs.


Methanethiol is a colorless but malodorous gas derived from the brain and blood of humans and other animals. Methanethiol does exist in the brain and blood of living humans. It is released from the body during the human decomposition process. Methanethiol has the odor of rotten cabbage.

Dimethyl Disulfide

Dimethyl disulfide is a foul-smelling gas derived from many sources, including bacteria, fungi, plants, and animals. Rotting meat gives off this gas. It is the smell associated with dimethyl disulfide that tends to attract flies to a decomposing body. Dimethyl disulfide has the odor of foul garlic.

Dimethyl Trisulfide

Dimethyl trisulfide is foul smelling and commonly is emitted from onions, leek, broccoli, and cabbage. It is also detectable with decomposing human remains. Dimethyl trisulfide has the odor of foul garlic.

Hazards of a Decomposing Human Body

In addition to dangerous pathogens that can be found in blood, bodily fluids, and other biological matter associated with a decomposition human body, the gases emitted from remains can present at least some threat to the health of living individuals. For this reason, when a person is in the direct vicinity of a decomposing human body, taking appropriate safety precautions is vital. This includes the wearing of appropriate personal protective equipment that includes:

  • Goggles
  • Gloves
  • Smock, apron, or uniform
  • Respirator or mask

The Stages of Human Decomposition

There generally are considered to be five stages associated with the human decomposition process. These five stages are:

  • Fresh State
  • Putrefaction State
  • Active Decay State
  • Advanced Decay State
  • Skeletonization State

The Fresh States persists for the first couple of days following the death of a human being. After the second day mark, the Putrefaction Stage commences. It is at this stage that the stench of decomposition begins to occur. The smell of death will persist, at least to some degree, up to and until the Skeletonization State. Once a cadaver reaches the Skeletonization State virtually everything that is capable of decomposition has decomposed. Thus, there remains virtually nothing in the way of gases to be released from the decomposing human remains.

Understanding the specifics of the human decomposition process is vital when it comes to ascertaining the cause of death. It is also vital in regard to the process utilized to clean up a death scene or to undertake biohazard remediation.


Emily Kil

Co-Owner of Eco Bear Biohazard Cleaning Company

Together with her husband, Emily Kil is co-owner of Eco Bear, a leading biohazard remediation company in Southern California. An experienced entrepreneur, Emily assisted in founding Eco Bear as a means of combining her business experience with her desire to provide assistance to people facing challenging circumstances. Emily regularly writes about her first-hand experiences providing services like biohazard cleanup, suicide cleanup, crime scene cleanup, unattended death cleanup, and other types of difficult remediations in homes and businesses.