Addictive Substances and the Digestive System

The harms of addictive substances to the brain, the heart and the lungs are better known. But these substances can also affect many parts of the digestive system, from the oesophagus to the stomach, and from the bowels to the liver and the pancreas.

The effects on the digestive system vary with the kind of substance used, the amount, how long it has been used and how it is taken.

Some substances slow the movements of the bowel seriously, while others can disturb its blood supply. Others can contribute to recurrent vomiting, liver damage or diseases of the pancreas.

How do opioids affect the digestive system?

Opioids include heroin and illicit synthetic opioids, as well as strong painkillers used for medical purposes such as morphine, oxycodone and fentanyl.

Using these drugs for medical purposes under a doctor’s supervision is not the same thing as using them without supervision or illicitly. But the basic effects of opioids on the bowel are similar.

Opioids slow the movements of the bowel.

The result may be:

• Constipation,
• Hard stools,
• Straining,
• Bloating of the abdomen,
• Wind,
• Abdominal pain,
• Difficulty opening the bowels.

This picture may broadly be called opioid-induced bowel dysfunction.

Why does opioid-induced constipation matter?

Constipation is very common in people taking opioids.

Although the bowel may become accustomed over time to some of the effects of opioids, tolerance to the constipation mostly does not develop sufficiently. The problem can therefore continue throughout treatment.

In severe cases there may be:

• Stool becoming impacted in the bowel (faecal impaction),
• Haemorrhoids,
• An anal fissure,
• Abdominal pain and excessive bloating,
• Rarely, serious bowel problems.

In patients who need to take opioids for a long period, it matters that the constipation is assessed from the outset and that preventive treatment is planned where needed.

What is narcotic bowel syndrome?

An interesting situation can develop in some people taking opioids for a long time or at high doses.

While the opioid was taken at first to reduce pain, over time it may contribute to the abdominal pain becoming more frequent and more severe.

This is called narcotic bowel syndrome.

As the pain increases the patient may take more opioid, but this can create a cycle in which the pain gets worse still.

Treatment of this condition must be carried out under medical supervision.

How does cocaine affect the digestive system?

Cocaine has a powerful vasoconstrictor effect.

As the vessels supplying the digestive system narrow, the amount of blood reaching the bowel may fall.

This can lead to a serious condition called bowel ischaemia.

The symptoms may be:

• Sudden, severe abdominal pain,
• Bloody stools,
• Nausea and vomiting,
• Tenderness of the abdomen.

In advanced cases, damage to the bowel tissue, perforation of the bowel and inflammation of the lining of the abdomen may develop.

Severe abdominal pain or bloody stools appearing after cocaine use require emergency assessment.

Methamphetamine and other powerful stimulants

Methamphetamine and similar powerful stimulants can also cause narrowing of the blood vessels and disturbance of the body’s normal circulation.

As far as the digestive system is concerned, there may be:

• Loss of appetite,
• Nausea,
• Abdominal pain,
• Weight loss,
• Nutritional deficiency.

In more severe situations, ischaemic damage to the bowel may develop as a result of reduced blood flow to it.

How does cannabis affect the digestive system?

The effects of cannabis on the digestive system differ from those of the other substances.

In some people there may be:

• Dryness of the mouth,
• Changes in appetite,
• Nausea,
• Abdominal pain,
• Changes in bowel movements.

But there is an important condition that can appear with long-term, frequent use in particular.

What is cannabinoid hyperemesis syndrome?

In some people using cannabis heavily over a long period, recurrent attacks of severe nausea and vomiting can develop.

This is called cannabinoid hyperemesis syndrome (CHS).

The patient may have:

• Recurrent nausea,
• Severe vomiting,
• Abdominal pain,
• Fluid loss,
• Electrolyte disturbances.

Interestingly, some patients report that their complaints lessen temporarily when they take a hot shower or bath.

This feature can be an important clue to CHS.

But a hot shower is not a treatment for the condition.

The lasting solution is stopping cannabis.

If use continues, the attacks can return.

Why is recurrent vomiting dangerous?

Whatever the substance, long-standing or recurrent severe vomiting can lead to problems such as:

• Dehydration,
• Disturbances of sodium and potassium,
• Deterioration of kidney function,
• Damage to the oesophagus.

Very violent retching and vomiting can cause small tears at the junction of the oesophagus and the stomach. This is called a Mallory-Weiss tear, and it can lead to vomiting blood.

Can the liver be affected?

Yes.

Here the cause of the harm may not be the substance itself alone.

With intravenous use in particular, the risk of blood-borne viral infections such as:

• Hepatitis B,
• Hepatitis C

rises considerably.

Sharing needles or injecting equipment can cause these viruses to pass from person to person.

Some substances, or unknown substances mixed into them, may also have direct toxic effects on the liver.

Can the pancreas be affected?

Certain addictive substances, and substances used alongside them such as alcohol, can be associated with the development of acute pancreatitis.

Acute pancreatitis typically presents with:

• Severe pain in the upper abdomen,
• Pain going through to the back,
• Nausea,
• Vomiting.

But because pancreatitis has many different causes — gallstones and alcohol chief among them — other possibilities have to be assessed before the substance used is accepted as the cause on its own.

Why does the route of use matter?

How the substance is taken into the body also affects the problems that may arise.

Intravenous use in particular poses an important risk of:

• Hepatitis B,
• Hepatitis C,
• HIV,
• Serious bacterial infections.

Sharing needles, syringes or other injecting equipment increases this risk further still.

Using more than one substance together

Using addictive substances together with:

• Alcohol,
• Sedative medicines,
• Opioids,
• Other narcotic or stimulant substances

can make the effects unpredictable and far more dangerous.

As far as the digestive system is concerned, the risk of vomiting, aspiration, liver damage and other complications may increase.

Beyond that, serious consequences far outside the digestive system may follow, such as suppression of breathing, loss of consciousness and death.

When is emergency help needed?

The development after substance use of:

• Severe or increasing abdominal pain,
• Vomiting blood,
• Black stools,
• Bloody stools,
• Vomiting that will not stop,
• Marked swelling of the abdomen with an inability to pass wind or stool,
• Jaundice,
• Fainting,
• A change in consciousness,
• Slowed or difficult breathing

requires emergency medical assessment.

Does stopping substance use improve the digestive system?

In many situations, yes.

With stopping the substance used, some digestive problems may settle completely or lessen markedly.

For instance:

• In cannabinoid hyperemesis syndrome, stopping cannabis can make the attacks disappear.
• Reducing opioid use appropriately can help the movements of the bowel to recover.
• Stopping intravenous use reduces the risk of new blood-borne infection.
• The nutritional state may improve over time.

But in people who have developed dependence, stopping the substance may require medical support.

Stopping opioids and certain sedative medicines suddenly and without supervision in particular may not be appropriate. Treatment should be planned for the individual.

The important message

Addictive substances can affect seriously not only the brain and mental health but the digestive system too.

Opioids slow the movements of the bowel and can lead to serious constipation.

Cocaine and powerful stimulants narrow the vessels of the bowel and can, though rarely, cause bowel ischaemia that can threaten life.

Long-standing, heavy cannabis use can lead to cannabinoid hyperemesis syndrome, which runs with recurrent severe vomiting.

Intravenous use considerably increases the risk of transmission of infections such as hepatitis B and hepatitis C.

Where there are symptoms such as severe abdominal pain, bloody stools, vomiting blood or vomiting that will not stop, medical help should be sought without delay.

This content has been prepared for general information. The diagnosis and treatment of digestive problems related to substance use vary with the substance used and with the person’s state of health, and should be assessed by a doctor.