Why Does Heroin Make You Throw Up?

Clear Treatment

Heroin is in a class of drugs known as opioids. Many people think that when a person uses heroin they just get high. But that is not the entire story. Heroin, much like any other opioid, produces several unpleasant after effects as well, two of which are nausea and vomiting. Nausea is the discomfort that is felt before vomiting, and vomiting refers to the expulsion of stomach contents via the mouth.

Heroin, the Brainstem and Vomiting

Heroin induced nausea and vomiting are actually normal functions of the Medulla Oblongata. The medulla oblongata is located at the lower brain stem. It runs continuous with the spinal cord, which means that there is no clear delineation between the spinal cord and medulla oblongata, but rather a gradual transition into the spinal cord. The medulla oblongata is also the oldest part of the nervous system, thus responsible for many involuntary functions, such as heart rate, breathing, sneezing, swallowing, coughing, and vomiting. For these reasons, the medulla oblongata is considered the most important part of your brain.

The Medulla Oblongata is in a unique position to detect poisonings, because it’s not protected by a blood-brain-barrier. In other words, the Medulla Oblongata is in the one location that can sense opioids before they affect the rest of the brain.

Chemoreceptor Trigger Zone

It’s actually the chemoreceptor trigger zone (CTZ) within the Medulla Oblongata that detects opioids such as heroin. If a sufficient quantity of opioids are streaming through your bloodstream the CTZ recognizes it as poison. The CTZ then directs your stomach to throw up. A common misconception is to think that the stomach tells the brain it’s going to throw up, when in fact, it’s the brain commanding the stomach to throw up.

The Process of Throwing-Up

  • Stimulation of the CTZ leads to the activation of the Central Nervous System, Parasympathetic Nervous System and the Sympathetic Nervous System
  • Stimulation of the parasympathetic nervous system causes increased salivation
  • Deep breathing precedes vomiting to protect the lungs from aspiration
  • Heaving or retching occurs just before vomiting
  • Relaxation of the pyloric sphincter that guards the lower end of the stomach to bring up content from the gut
  • Abdomen pressure rises and the pressure within the chest or thorax lowers.
  • The abdominal muscles contract and expels the contents within the stomach
  • Activation of the sympathetic nervous system leads to sweating, palpitation and rapid heart rate

Opiate induced vomiting

We know that within hospitals, nausea occurs in 25 – 30 percent of patients treated with opiates. Since heroin involves greater average dosing and subsequent amplified effects, it results in higher than average emetic responses. Another interesting opiate fact is that nausea and vomiting occurs more often in blacks than whites and more often in women than men.

The first time a person uses heroin or any other type of opiate they become susceptible to vomiting. It’s not a rule that a new heroin user will get nauseous and throw up, but it’s quite common. Furthermore, many longer-term heroin addicts glean pleasure from vomiting after using, mainly because they perceive it to mean “strong heroin.”


Nausea is a highly distressing queasy feeling that may or may not result in vomiting. We know that “tolerance” develops to both heroin induced nausea and vomiting, and over time, both of these uncomfortable effects fade away.

Throwing-Up is the expulsion of your stomach contents through your mouth. There are two phases to throwing up, (1) the retching phase, which is recognized by stomach contractions without expulsion, followed by (2) the expulsion phase. The vomitus is generally highly acidic and malodorous.

The first line of defense against opiate induced nausea and vomiting might be to stop taking opioids (painkillers or heroin). Another common treatment for nausea and vomiting is administration of an anti-emetic.