Endocannabinoid System: A Simple Guide To How It Works

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HealthlineSubscribeA Simple Guide to the Endocannabinoid System

Medically reviewed by Kelsey Nank, PA-C — Written by Crystal Raypole — Updated on April 28, 2025

How it works
Functions
THC
CBD
Deficiency
Takeaway

The endocannabinoid system (ECS) is a complex cell-signaling system that helps regulate your body functions, including sleep and mood, among others.

It was identified in the early 1990s by researchers exploring THC, a well-known cannabinoid. Cannabinoids are compounds found in cannabis.

Experts are still trying to fully understand the ECS. But so far, we know it plays role in regulating a range of functions and processes, including:

sleep
mood
appetite
memory
reproduction and fertility
immune function
pain control

The ECS exists and is active in your body even if you don’t use cannabis.

Read on to learn more about the ECS including how it works and interacts with cannabis.

How does it work?

The ECS involves three core components: endocannabinoids, receptors, and enzymes.

Endocannabinoids

Endocannabinoids, also called endogenous cannabinoids, are molecules made by your body. They’re similar to cannabinoids, but they’re produced by your body.

Experts have identified three key endocannabinoids so far:

anandamide (AEA)
2-arachidonoylglyerol (2-AG)
pentadecanoylcarnitine, which is derived from an essential fatty acid called pentadecanoic acid (C15:0), found in trace amounts in dairy products

These help keep internal functions running smoothly. Your body produces them as needed, making it difficult to know what typical levels are for each.

Endocannabinoid receptors

These receptors are found throughout your body. Endocannabinoids bind to them in order to signal that the ECS needs to take action.

There are two main endocannabinoid receptors:

CB1 receptors, which are mostly found in the central nervous system
CB2 receptors, which are mostly found in your peripheral nervous system, especially immune cells

Endocannabinoids can bind to either receptor. The effects that result depend on where the receptor is located and which endocannabinoid it binds to.

For example, endocannabinoids might target CB1 receptors in a spinal nerve to relieve pain. Others might bind to a CB2 receptor in your immune cells to signal that your body’s experiencing inflammation, a common sign of autoimmune disorders.

Enzymes

Enzymes are responsible for accelerating biochemical reactions and breaking down endocannabinoids once they’ve carried out their function.

There are two main enzymes responsible for stimulating the endocannabinoids’ effects on the body:

1,2-diacylglycerol lipase
phospholipase A

And the two main enzymes that break down endocannabinoids are:

fatty acid amide hydrolase, which breaks down AEA
monoacylglycerol acid lipase, which typically breaks down 2-AG

What are its functions?

The ECS is complicated, and experts haven’t yet determined exactly how it works or all of its potential functions.

Research has linked the ECS to the following processes:

appetite and digestion
metabolism
chronic pain
inflammation and other immune system responses
mood
learning and memory
motor control
sleep
cardiovascular system function
muscle formation
bone remodeling and growth
liver function
reproductive system function
stress
skin and nerve function

These functions all contribute to homeostasis, which refers to stability of your internal environment. For example, if an outside force, such as pain from an injury or a fever, throws off your body’s homeostasis, your ECS kicks in to help your body return to its ideal operation.

Today, experts believe that maintaining homeostasis if the primary role of the ECS.

How does THC interact with the ECS?

Tetrahydrocannabinol (THC) is one of the main cannabinoids found in cannabis. It’s the compound that gets you “high.”

Once in your body, THC interacts with your ECS by binding to receptors, just like endocannabinoids. It’s powerful partly because it can bind to both CB1 and CB2 receptors.

This allows it to have a range of effects on your body and mind, some more desirable than others. For example, THC may help to reduce pain and stimulate your appetite. But it can also cause paranoia and anxiety in some cases.

Experts are currently looking into ways to produce synthetic THC cannabinoids that interact with the ECS in only beneficial ways.

How does CBD interact with the ECS?

The other major cannabinoid found in cannabis is cannabidiol (CBD). Unlike THC, CBD doesn’t make you “high” and typically doesn’t cause any negative effects.

Experts aren’t completely sure how CBD interacts with the ECS. But they do know that it doesn’t bind to CB1 or CB2 receptors the way THC does.

Instead, many believe it works by preventing endocannabinoids from being broken down. This allows them to have more of an effect on your body. Others believe that CBD binds to a receptor that hasn’t been discovered yet.

While the details of how it works are still under debate, research suggests that CBD can help with pain, nausea, and other symptoms associated with multiple conditions.

What about endocannabinoid deficiency?

Some experts believe in a theory known as clinical endocannabinoid deficiency (CECD). This theory suggests that low endocannabinoid levels in your body or ECS dysfunction can contribute to the development of certain conditions.

A 2016 article reviewing over 10 years of research on the subject suggests the theory could explain why some people develop migraine, fibromyalgia, and irritable bowel syndrome.

None of these conditions have a clear underlying cause. They’re also often resistant to treatment and sometimes occur alongside each other.

If CECD does play any kind of role in these conditions, targeting the ECS or endocannabinoid production could be the missing key to treatment, but more research is needed.

The bottom line

The ECS plays a big role in keeping your internal processes stable. But there’s still a lot we don’t know about it. As experts develop a better understanding of the ECS, it could eventually hold the key to treating several conditions.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Kelsey Nank, PA-C — Written by Crystal Raypole — Updated on April 28, 2025

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