Horripilation is the medical term for goose bumps or goose pimples. Feeling cold and experiencing emotions like excitement and fear are common causes.

Horripilation is an involuntary reaction, which means it happens automatically and a person cannot control it. The phenomenon is completely normal and harmless and should resolve on its own.

Read on to learn about what horripilation is, why it happens, and more.

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Horripilation is when small bumps develop on a person’s skin, underneath the hair follicles. This is an involuntary reaction controlled by the sympathetic nervous system.

Hair follicles contain tiny muscles called arrector pili muscles. When these muscles contract, they pull the hair upright, causing horripilation. These bumps are temporary and usually disappear in a short period of time without treatment.

However, some conditions may cause a person to have something similar to horripilation for longer periods of time.

For example, keratosis pilaris can leave bumps on the skin. They may feel itchy, rough, and dry, and they are usually worse in winter.

The following are some common causes of horripilation.

Being cold

The most common reason for developing goose bumps is being cold.

When a person gets cold, their brain sends signals to certain parts of their body. One of these signals may go to the muscles in hair follicles. When they contract, the hairs stand upright, which can help retain warm air in an effort to conserve body heat.

Horripilation can also occur in animals. It works better for most animals because they typically have more hair than humans.

If coldness is the cause, horripilation will usually go away once a person warms up. However, if the bumps and other coldness symptoms remain, a person may have hypothermia and should seek medical assistance.


Strong emotions, arousal, or motivation may also cause goose bumps.

This happens because the hair erecting muscles are part of the sympathetic nervous system. When stimulated by brain signals, the muscles contract, making the hairs stand up.

Emotions that may cause horripilation include fear, shock, anxiety, love, sexual desire, and inspiration.

Older research from 2011 claims that when goose bumps result from emotional stimulation, a person may also experience sweat and heavy breathing. In animals, this frequently happens when they become scared, as it makes them look larger. This is the same emotional response that occurs in humans.

Medical conditions

Some medical conditions may cause horripilation. They include:

  • Temporal lobe epilepsy: This is a rare condition that causes seizures. It can begin at any age and usually occurs because a person has had a seizure with a fever or a brain injury. Seizures with this type of epilepsy begin in the sympathetic nervous system, so they can cause goose bumps.
  • Keratosis pilaris: This skin condition is caused by dead skin cells on the upper arms, the front of the thighs, the cheeks, and the bottom. It results in dry and rough bumps that may resemble goose bumps. It usually clears up on its own or with certain creams.
  • Automatic dysreflexia: This is when a person with a spinal cord injury has very high blood pressure. The goose bumps usually occur above the point of the injury. Other symptoms include extreme headache, cool and pale skin, vision problems, a blocked nose, dizziness, and nausea.
  • Drug withdrawal: If a person is experiencing withdrawal, they may get a fever. Because a person feels cold when they have a fever, goose bumps can occur.

A person may also experience goose bumps if they have any illness that results in fever. This is because the body believes itself to be cold, causing the brain to stimulate reactions to make the body warmer.

Some drugs, such as methamphetamine and milnacipran hydrochloride, may also cause horripilation.

Horripilation is a very common and normal body response. It is not harmful and does not require medical attention. The bumps usually go away within a short period of time.

As mentioned above, horripilation may occur as a result of an underlying medical condition. If a person thinks they have one of these underlying conditions, they should contact a healthcare professional.

Additionally, if a person’s goose bumps do not go away, they should seek medical attention.

Goose bumps are not completely preventable, and there is no real reason to try to prevent them. However, if a person wishes to try to avoid them, they could take the following steps:

  • Stay warm outdoors by dressing appropriately.
  • Avoid high air conditioning and drafts when indoors.
  • Add more clothing layers or use a blanket when cold.
  • Try to stay calm when experiencing strong emotions.
  • Avoid taking illegal drugs.

To avoid developing conditions such as keratosis pilaris, a person can exfoliate their skin well and regularly.

Horripilation is most commonly known as goose bumps or goose pimples. These are bumps on the skin that occur when the hair follicle muscles stand erect.

In some cases, this may be a sign of a more serious health condition, but it usually occurs because a person is cold or experiencing strong emotions. It is not harmful and does not require treatment.