Check out the courses we offer
Knowledge Base » Care » What is Morphine?

What is Morphine?

Morphine is an opioid used for pain management. Recent research by The Lancet has shown that the UK consumes the highest amount of prescription opioids per capita on the planet. Though the amount of prescription opioids like morphine has declined slightly in the last six years, the UK has not kept up with the huge decreases in other countries like Canada, Germany and the United States.

In 2019, the United Kingdom consumed 1353 MMEs (morphine milligram equivalents) per day for each 1000 inhabitants. This was much higher than in Canada (1039 MMEs), the U.S. (1101 MMEs) and Germany (1104 MMEs).

According to the World Health Organization, around half a million global deaths each year are attributable to the use of drugs. 70% of these are due to opioids like morphine.

But what is morphine and what is it used for? This article will tell you everything you need to know – the good, the bad and the ugly.

What is morphine?

Morphine is an opiate, which is a substance that has derived from opium. Opium comes from the seed capsules of a specific type of poppy – the opium poppy or Papaver somniferum. Morphine is a strong drug whose primary use is as a strong pain medication. It is, however, commonly used to create illicit opioids.

There are many ways to administer morphine. It can be given intravenously, by injection under the skin or into a muscle, by inhalation, sublingually, rectally or orally. The drug acts on the central nervous system to alter pain perception and emotional response to pain. It also induces analgesia. With repeated doses, it is possible to become psychologically and physically dependent on morphine or to develop a tolerance.

Common uses include for trauma, kidney stones, heart attacks and during labour.

Morphine through IV line

Is morphine addictive?

Even when morphine is prescribed, it can become addictive. Any form of morphine can lead to addiction. This is because, like all opioids, morphine travels through the blood and attaches itself to brain cell receptors to boost pleasurable feelings and reduce pain. Over time, a person can seek those pleasurable feelings even when they are no longer in pain.

Morphine works for pain relief because it mimics endorphins, which block pain and increase feelings of wellbeing. Essentially, taking morphine can give a person a feeling like a rush of endorphins.

When someone is addicted to morphine, there will be signs.

These include:

  • Short-term effects like dilated pupils, slower breathing, nausea, lethargy, sleepiness, chills and sweats.
  • Long-term effects like severe constipation, depression, poor or erratic sleep, kidney problems and body tremors.
  • Changes in behaviour like becoming withdrawn and antisocial, lying, stealing, neglecting responsibilities, aggression or being highly irritable.

Is morphine illegal in the UK?

Like other opiates, morphine is a controlled drug as per the Misuse of Drugs Act. It is a Class A drug and unauthorised possession could lead to a fine, seven years in prison, or both. For producing or supplying morphine, you could receive a fine, life imprisonment, or both.

It is, however, available legally on prescription. It can be prescribed in many forms for home use or hospital use. Since it’s a controlled medicine, you will be required to sign your prescription and show proof of identity when collecting it from a pharmacy.

How is morphine used?

Morphine is used for pain relief and is used in a variety of ways. When patients are prescribed the drug, they will be given clear guidance on how to use it.

For those who are likely to need morphine for a short time, injections, liquid or tablets might be given. For long-term pain, patients are often given slow-release tablets or granules that work over a period of 12 to 24 hours. Though this takes a longer time to kick in, it will last longer.

How does morphine work?

Morphine is absorbed into the blood and is delivered to the organs. The muscles and brain will get a lower concentration of the drug than other areas like the liver, lungs and kidneys. The biggest effects of morphine are in the central nervous system, in different receptor branches (m/k/d receptors). When morphine binds to these receptors, it stimulates parts of the brain and reduces nerve transmission from the periphery to the brain.

Let’s take a look at how the different receptors are involved in bodily functions.

M1 receptors

These are involved in analgesia, decreased gastrointestinal activity, euphoria, pain modulation, respiratory depression, and miosis (pupil constriction).

M2 receptors

These are involved in mental clouding, drowsiness, respiratory depression and nausea.

K receptors

These are involved in diuresis (increased production of urine), dysphoria, analgesia, mild respiratory depression, sedation and miosis.

D receptors

These are involved in analgesia, dysphoria, hallucinations and delusions.

Woman taking tablet form of morphine

How is morphine abused?

Morphine is mainly abused for the state of bliss and pleasurable feeling it causes. When it is prescribed on a long-term basis for chronic pain, most people will grow a dependence and tolerance. It’s possible for anyone to develop an opioid use disorder as a result of long-term morphine use.

The definition of morphine abuse is when someone is using the drug without a prescription. Morphine is legal when it is prescribed but other uses are illegal.

Morphine is abused in the following ways:

  • Using another person’s medication.
  • Using more than has been prescribed (thus building a tolerance).
  • For recreational purposes.

Abusing morphine increases a person’s risk of addiction and overdose.

Short-term abuse can have the following effects:

  • Drowsiness.
  • Nausea.
  • Constipation.
  • Vertigo.
  • Depression.
  • Poor judgement.
  • Inability to focus.
  • Impaired mental performance.
  • Being preoccupied with the drug.

Extended morphine abuse will lead to damage to mental and physical health. Sustained morphine abuse also leads people to begin experimenting with other drugs and even heroin.

Long-term effects of morphine abuse include:

  • Lung failure.
  • Respiratory failure.
  • Circulation damage.
  • Hallucinations.
  • Confusion.
  • Losing consciousness.
  • Asphyxiation.
  • Anaemia.
  • Coma.

How does morphine affect the body?

Using morphine will provide pain relief but it also has other effects on the body. It suppresses the cough reflex, for example, and also decreases your appetite.

In terms of common side effects, over 1% of people experience the following:

  • Constipation.
  • Nausea.
  • Vomiting.
  • Sleepiness/lethargy.
  • Vertigo or dizziness.
  • Headaches.
  • Confusion.
  • Itching skin or a rash.
  • Sweating.
  • Feelings of extreme sadness or happiness (dysphoria/euphoria).

It can also affect a person’s mood, heart rate and body temperature too.

Morphine will usually stay in a person’s system for a long time after they stop feeling its effects. It stays in saliva and blood for three days, urine for four days, breastmilk for 24 hours and can stay in your hair for up to three months.

Feeling of extreme euphoria due to morphine

What are the risks of morphine?

Like all strong drugs, taking morphine comes with risks. It is not advisable for people who have breathing difficulties like asthma to take the drug, for example. People who have a bowel or stomach obstruction are also recommended not to take it.

People who have had a brain tumour, seizures, head injuries, sleep apnoea, a mental illness, drug/alcohol addiction, kidney or liver disease, problems urinating, or problems with their thyroid, pancreas or gallbladder should inform a doctor before taking morphine as they will be at risk of their problems worsening.

Besides addiction, morphine can cause other problems.

Firstly, some people are allergic to it. This can cause allergic reactions like swelling of the lips, tongue, throat and face, difficulty breathing and hives. It can also cause slow breathing, breathing that has long pauses and blue lips due to inadequate oxygen intake.

It can also cause chest pain, heart palpitations, a slow heart rate and feeling faint.

Taking morphine is known to cause serotonin syndrome. This presents as hallucinations, agitation, a fast heart rate, fever, muscle twitches, nausea, diarrhoea and poor coordination.

Finally, it can demonstrate as low cortisol levels, which causes loss of appetite, nausea, vomiting, dizziness, weakness and tiredness.

When people have existing medical problems, particularly older people or those with chronic breathing problems, they can have serious problems.

Signs and symptoms of morphine overdose

There are signs to look out for if you suspect someone has taken a morphine overdose.

These include:

  • Clammy and cold skin.
  • Extreme sleepiness.
  • Slowed breathing.
  • Slurred speech.
  • High blood pressure.
  • Inattention.
  • Pain in lower back or side.
  • Fever.
  • Being unresponsive or reduced responsiveness.
  • Spasms or muscle twitches.
  • Muscle cramps.
  • Swelling of face or extremities.
  • Lack of movement.

These symptoms happen due to morphine’s depressant effect on the central nervous system. Ultimately, a morphine overdose can lead to unconsciousness, coma and death.

Short-term and long-term effects of morphine

Morphine creates feelings of intense relaxation and euphoria as well as pain relief. Though these effects are positive, there are also negative effects too.

Side effects range from mildly annoying to fatal.

They can include:

  • A loss of appetite.
  • Nausea.
  • Vomiting.
  • Itchy skin.
  • Urinary retention.
  • Slowed or shallow breathing.
  • Constipation.
  • Constricted pupils.
  • Irregular or altered heart rhythm/rate.
  • Cyanosis (a blue tint to lips, skin and fingernails).
  • Chest pain.
  • Confusion.
  • Agitation.
  • Dizziness.
  • Seizures.

In terms of long-term effects, the most important potential effect is addiction. As well as having numerous health complaints associated with opiate use, morphine addiction causes people to lose interest in their friends, family and work. It also means people end up prioritising finding and using the drug above everything else, including health and finances.

As such, many people who find themselves addicted to morphine also become involved in crime like stealing. What’s more, because continuous use creates a tolerance, people need more of the drug (or a different drug like heroin) to receive the same hit.

When addiction sets in, risks increase further as withdrawal symptoms can make even the most strong-willed give up trying.

Feeling dizzy due to medication

What are the different forms of morphine?

Morphine sulphate, as a drug, is one of the most feared and misunderstood medicines used in the treatment of pain.

Morphine comes in many different forms, which include:

  • Standard tablets (containing 10 mg, 20 mg or 50 mg).
  • Slow-release tablets (containing 5 mg, 10 mg, 15 mg, 30 mg, 60 mg, 100 mg or 200 mg).
  • Slow-release capsules (containing 10 mg, 30 mg, 60 mg, 90 mg, 100 mg, 120 mg, 150 mg or 200 mg).
  • Granules (these are mixed into water to drink and contain 20 mg, 30 mg, 60 mg, 100 mg or 200 mg).
  • A liquid (10 mg/5ml or 20 mg/1ml).
  • Injection.
  • Suppository.

The dose given will depend on the reason and pain level.

Oral solutions

Liquid morphine is often administered for palliative care. It is easy to give to patients and can be given in large doses with a small amount of liquid. When people are unable to swallow tablets or aren’t very conscious, liquid morphine can be easier to administer.

This form of morphine usually works within quarter of an hour and will provide pain relief for around four hours. Doses need to be accurate due to how highly concentrated the solution is.

Capsule or tablet forms of morphine

Both of these come in slow-release or rapid-release forms.

The rapid-release tablets work like the liquid solution and will only last for four hours. These can be taken crushed or mixed in food if someone finds swallowing difficult. They can even be administered crushed through an NG (nasogastric) tube.

Slow-release tablets, however, should never be crushed or halved. This is because it will stop their slow release. They can be taken once or twice a day.

Injectable morphine

Morphine can be injected either under the skin as a subcutaneous injection or into a muscle as an intramuscular injection. It can also be delivered through an IV (intravenous infusion).


For people who can’t swallow morphine liquid or tablets, a suppository can be administered and inserted into the rectum.

Final thoughts on ‘What is morphine?’

While morphine is a controlled drug and an addictive one, there’s no doubt that it’s a beneficial substance for many patients with acute and chronic pain as well as those on end-of-life care. Provided that the drug is carefully prescribed and administered, the effects can be limited and the likelihood of dependence and addiction can be reduced.

Pain Management Course

Pain Control and Management in Care

Just £20

Study online and gain a full CPD certificate posted out to you the very next working day.

Take a look at this course

About the author

Avatar photo

Louise Woffindin

Louise is a writer and translator from Sheffield. Before turning to writing, she worked as a secondary school language teacher. Outside of work, she is a keen runner and also enjoys reading and walking her dog Chaos.

Similar posts