How long does heroin stay in your system?

Marie Law Alphabiolabs

By Marie Law, Head of Toxicology at AlphaBiolabs
Last reviewed: 22/03/2023

Heroin is a highly addictive Class A substance and the most commonly injected drug in the UK.

In this article, we take a closer look at heroin, why it’s addictive, how long it stays in your system, and the long-term effects of heroin use.

Table of contents
  • What happens in the body when you take drugs?
  • What is heroin?
  • What does heroin do to you?
  • Is heroin addictive?
  • How long does heroin stay in your system?
  • How long does it take for heroin to show up in a drug test?
  • What factors affect how long heroin stays in your system?
  • What are the long-term effects of heroin use?
  • What are the signs of heroin addiction?
  • How can I find out if a loved one is using heroin?

What happens in the body when you take drugs?

When a person consumes drugs, they are broken down by the liver, and a proportion of the drug and its metabolites are released into the bloodstream.

Some of the drug and its metabolites can then be detected in the body in different ways including via sweat, urine, saliva, hair and nails.

In the case of hair and nails, a proportion of the drug and its metabolites travel to the blood vessels in the scalp and nail bed.

Substances then become trapped in the hair shaft (medulla) and the keratin fibres of the nails, remaining in hair and nails as they grow, and making it possible to determine whether someone has consumed drugs, using hair and/or nail testing.

What is heroin?

Heroin, also known by the street names smack, gear and skag, is an opioid drug made from morphine, a natural substance taken from the seed pods of various opium poppy plants, which grow in southeast and southwest Asia, Mexico and Colombia.

It is usually sold as a white or brownish powder, or as a black sticky substance known as ‘black tar heroin’.

Heroin is also sometimes referred to as diacetylmorphine or diamorphine.

Although heroin and diamorphine are structurally the same, there are fundamental differences between the two. Diamorphine is a legal, strong and effective painkiller that is often used by the medical profession to relieve pain in patients after surgery, or for cancer patients.

Heroin is typically produced and distributed illegally for recreational (illegal) drug use.

Recreational drug users usually inject, snort, or smoke heroin. When smoked, the drug is heated on a surface such as tin foil, before the smoke is inhaled.

It can also be dissolved in water and then injected – this is an extremely dangerous method that has a higher risk of overdose.

What does heroin do to you?

Some people who take heroin may experience feelings of euphoria or a surge of pleasure known as a ‘rush’ or ‘high’. However, the drug can also cause feelings of anxiety and paranoia.

The side effects of heroin depend on several factors including how the drug is taken, how often it is used and the metabolism and build of the person using it.

Some common side effects of heroin use include:

  • Drowsiness
  • Dry mouth
  • Short-term memory loss
  • Dizziness
  • Vomiting

When injected, other harmful effects include collapsed veins, infections, and blood clots.

A person who injects heroin is also at an increased risk of overdosing or contracting life-altering infections such as HIV, hepatitis B and hepatitis C. This risk is even greater among users who share needles.

Is heroin addictive?

Heroin is extremely addictive. Users often develop a tolerance for it over time, requiring them to take more of the drug more frequently, to experience the same ‘high’.

This can lead to an extremely harmful addiction or dependency.

A person who is addicted to heroin and stops using the drug abruptly can experience severe withdrawal symptoms that can begin as early as a few hours after the drug was last taken. These symptoms include:

  • Restlessness
  • Severe muscle and bone pain
  • Sleep problems
  • Diarrhoea and vomiting
  • Feeling cold with goose bumps – known as ‘going cold turkey’
  • Uncontrollable leg movements – where the phrase ‘kicking the habit’ comes from
  • Severe heroin cravings

As these symptoms can last for weeks or months, symptoms of heroin withdrawal can be very uncomfortable and distressing, leading many to return to heroin use.

How long does heroin stay in your system?

How long heroin remains in the system can depend on several factors including how the drug is ingested, how often it is used, and the metabolism and weight of the individual.

Heroin is a relatively short-acting drug. This means that although the user will feel the effects of the drug almost immediately, the parent drug itself will not stay in a person’s system for very long.

However, metabolites from heroin – substances that are formed in the body as the drug breaks down – will remain in the body for much longer.

Once injected or smoked, heroin rapidly converts to the metabolite 6-monoacetylmorphine (6-MAM) in the body and then more slowly into morphine.

This means that heroin use can be detected by an oral fluid drug test from 30 minutes up to 48 hours after consumption, for several days in urine, and for up to 12 months in hair and nails.

How long does it take for heroin to show up in a drug test?

Even after the ‘high’ has worn off, and long after the drug was first consumed, heroin use can be detected by a drug test, depending on the type of test you take.

The drug testing detection windows for heroin are as follows:

  • Oral fluid (saliva) – up to 48 hours
  • Urine – up to 4 days
  • Hair – up to 12 months (depending on the length of hair available)
  • Nails – up to 12 months (up to 6 months for fingernails and up to 12 months for toenails)

Oral fluid and urine drug testing are known as ‘narrow-window’ forms of testing and can be used to detect drug use from 30 minutes after consumption, up to a few days. This can vary depending on the type of substance and how much was used.

The rate at which hair and nails grow means that both hair drug testing and nail drug testing can provide a ‘wide-window’ of detection for drugs and their metabolites (up to 12 months).

What factors affect how long heroin stays in your system?

How long heroin remains in the system depends on several factors including how the drug is taken (e.g. injected or smoked), how often it is used, how much is used, and the weight and metabolism of the person using it.

Drug purity and whether any other substances are taken at the time may also impact how quickly the body is able to process heroin.

What are the long-term effects of heroin use?

Heroin is highly addictive, so it can be very difficult for users to stop taking it once they have started.

Users can also build up a tolerance to the drug over time, meaning that they need more of it to achieve the same ‘high’.

This can lead to people taking heroin over long periods of time, increasing the risk of serious side-effects, and the potential for overdose.

Long-term heroin users may experience:

  • Insomnia
  • Damaged tissue inside the nose (from snorting the drug)
  • Infection of the heart lining and valves
  • Abscesses (swollen tissue filled with pus)
  • Constipation and stomach cramping
  • Liver and kidney disease

Long-term heroin use can also directly affect the brain, which may impact a person’s ability to make decisions, to regulate behaviour and to respond to stressful situations.

A long-term user who is injecting heroin is also at an increased risk of overdosing or contracting life-altering infections such as HIV, hepatitis B and hepatitis C, especially if they are sharing needles with others.

What are the signs of heroin addiction?

As heroin is one of the most addictive recreational drugs, there are plenty of signs to look out for in those you fear may have a problem with substance misuse.

Spotting the signs of heroin addiction as early as possible can help ensure your loved one gets access to the support they need to kick their habit.

Common signs you can look out for include:

  • Bloodshot eyes
  • Constricted pupils
  • Confused thinking or disorientation
  • Weight loss
  • Difficulty making decisions
  • Taking less care of their appearance
  • Falling asleep suddenly
  • Flushed skin
  • Itching
  • Loss of self-control
  • Memory loss
  • Nausea
  • Slow breathing
  • Vomiting

Further support and information on heroin addiction can be found on the NHS website.

How can I find out if a loved one is using heroin?

If you’re concerned that a loved one is using heroin, you can order one of our home drug tests today to get the answers you need.

AlphaBiolabs offers two types of home drug tests, designed to give you peace of mind or enable you to seek support for someone who is struggling with substance misuse.

  • Home Urine Drug Test Kit (£18) – this easy-to-use home drug testing kit can detect drugs and their metabolites in a urine sample. The self-contained screening kit includes built-in test strips, allowing you to read the results in just 5 minutes
  • Drug and Alcohol Nail Test (from £99) – this test can detect drug use for a period of up to 12 months prior to samples being collected, with only a sample of fingernail clippings or toenail clippings required. Simply follow the instructions included in your test kit to collect your nail clipping samples and return them to our accredited laboratory for testing

Please be aware that our home drug test kits are for peace of mind only, and the results cannot be used in court. If you require a drug test for official matters, you will need a legally-instructed drug test.

Home drug tests

Explore our range of at-home drug tests.

Marie Law

Marie Law

Head of Toxicology at AlphaBiolabs

A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team.

As Head of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public, the legal sector, and the workplace sector.

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