The Hidden Dangers of Nitazenes

Nitazenes are a serious threat to public health in the UK. These potent synthetic opioids have been found in illegal drugs, including heroin, counterfeit prescription medicines and some other substances. People may take them without knowing they are present, greatly increasing the risk of a fatal overdose.

First developed in the 1950s, nitazenes are a group of laboratory-made opioids. They act on the same opioid receptors as drugs such as morphine and fentanyl, but their strength varies considerably between individual compounds. Some nitazenes are substantially more potent than heroin or fentanyl, making even very small quantities potentially dangerous.

When this article was first published in January 2024, nitazenes were already linked to a growing number of overdoses. Since then, further deaths, changes to UK drug legislation and new public health guidance have demonstrated the continuing seriousness of the threat.

Why Are Nitazenes So Dangerous?

Nitazenes pose an extreme overdose risk because of their potency and the unpredictable nature of the illegal drug supply. Their effects include pain relief, sedation and slowed breathing. In an overdose, breathing can become dangerously slow or stop altogether.

Different nitazenes have different strengths. According to Public Health Scotland, some can be hundreds of times more potent than heroin. Etonitazene, for example, has been estimated to be around ten times more potent than fentanyl. These comparisons cannot be applied to every nitazene, and the strength of an unknown street drug cannot be judged by its appearance.

This extreme potency makes accurate dosing almost impossible, especially when nitazenes are mixed into street drugs of varying purity. A person who believes they are taking heroin or a prescription painkiller may unknowingly consume a much stronger opioid.

Nitazene overdoses can also develop rapidly. The speed and severity depend on the particular substance, the amount taken, how it enters the body and whether other drugs or alcohol have been used.

Combining nitazenes with other depressant substances, including benzodiazepines, alcohol or other opioids, can further increase the risk of respiratory depression, unconsciousness and death.

Can Naloxone Reverse a Nitazene Overdose?

Yes. Naloxone is an emergency medicine that can reverse the effects of an opioid overdose, including one involving nitazenes. It works by temporarily blocking the effects of opioids on the body.

However, nitazene overdoses may be particularly severe, and more than one dose of naloxone may be needed. Public Health Scotland advises that additional doses can be given at intervals of two to three minutes if the person does not respond, following the instructions supplied with the naloxone product.

Naloxone does not replace emergency medical treatment. Its effects can wear off while the opioid remains active, meaning that breathing difficulties may return. Anyone suspected of experiencing a nitazene overdose needs urgent medical attention, even if they initially recover after receiving naloxone.

For further information, see Public Health Scotland’s October 2026 nitazene guidance.

Overdose Symptoms and Risks

When taken unknowingly, nitazenes can easily lead to an overdose. Their potency means that a small amount can cause life-threatening effects. Signs of an opioid overdose include:

• Unresponsiveness or difficulty waking the person
• Slow, irregular or absent breathing
• Unusual snoring, gurgling or noisy breathing
• Very small or constricted pupils
• Pale, blue or grey lips and skin
• Severe drowsiness or loss of consciousness

Not everyone will show every symptom. If someone has taken drugs and becomes unresponsive or has difficulty breathing, treat the situation as a medical emergency.

What to Do in an Emergency

Call 999 immediately and ask for an ambulance. Explain that an opioid overdose may have occurred. If naloxone is available, administer it according to the product instructions and the emergency call handler’s advice.

If the person is unconscious but breathing normally, place them in the recovery position and continue monitoring their breathing. If they are not breathing normally, follow the emergency call handler’s instructions for CPR. Do not leave them alone while waiting for help.

Further guidance is available from the NHS and Public Health Scotland.

How Widespread Are Nitazenes?

Nitazene-related deaths have occurred across the UK, demonstrating that the problem is not confined to a single city or region. Nitazenes have been detected in drugs sold as heroin, counterfeit prescription tablets and other substances.

The National Crime Agency’s 2026 National Strategic Assessment reported 435 nitazene-related deaths in the UK during 2024 and a provisional 359 during 2025. The agency cautioned that the 2025 figure was expected to increase as further test results became available.

These figures come from national surveillance of deaths linked to synthetic opioids. They should not be confused with the Office for National Statistics’ figures based on death registrations, which use different reporting methods and time periods.

For comparison, the Office for National Statistics recorded 195 deaths involving nitazenes registered in England and Wales in 2024, compared with 52 in 2023. The figures show how rapidly nitazenes became a significant concern for public health authorities.

In Scotland, Public Health Scotland’s October 2026 guidance reports that nitazenes were implicated in 22% of drug-related deaths in 2025, compared with 8% in 2024. These are Scotland-specific figures and should not be interpreted as UK-wide prevalence.

Detecting nitazenes can also be challenging. Some routine drug screening methods do not identify every synthetic opioid, and laboratories may need specialised analytical techniques to confirm their presence.

Sources: National Crime Agency, 2026; Office for National Statistics, 2024 registrations; and Public Health Scotland, October 2026.

Nitazenes and UK Drug Law

Most nitazenes are controlled as Class A drugs under the Misuse of Drugs Act 1971.

In March 2024, the UK government brought 15 additional synthetic opioids, including 14 nitazenes, under Class A controls. Further legislation subsequently introduced a generic definition covering additional nitazene variants, helping prevent manufacturers from avoiding controls through small changes to chemical structures.

These changes reflect the government’s concern about the serious health risks associated with potent synthetic opioids. However, legal controls alone cannot eliminate the danger posed by substances circulating in the illegal drug market.

For details, see the Home Office announcement of March 2024 and the subsequent legislation introducing generic controls.

Key Facts

Some key facts about nitazenes:

• Nitazenes are a group of potent synthetic opioids originally developed in the 1950s.
• Different nitazenes vary considerably in strength, with some substantially more potent than heroin or fentanyl.
• They have been detected in drugs sold as heroin, benzodiazepines and counterfeit prescription painkillers.
• They can cause profound sedation, respiratory depression and fatal overdoses.
• Most nitazenes are controlled as Class A drugs in the UK.
• The National Crime Agency recorded 435 nitazene-related deaths in the UK in 2024.
• Naloxone can reverse a nitazene overdose, but repeated doses and emergency treatment may be necessary.

The Unpredictable Dangers of Street Drugs

The emergence of nitazenes highlights the unpredictable dangers of illicit drugs. Unregulated substances can contain unknown and hazardous ingredients, and the strength and composition of individual batches can vary considerably.

Someone purchasing heroin, a counterfeit prescription tablet or another street drug may have no reliable way of knowing whether a potent synthetic opioid is present. Nitazenes have also been found in products packaged to resemble legitimate medicines.

The danger is not limited to people with a history of opioid use. Someone without opioid tolerance may be especially vulnerable to severe respiratory depression if they unknowingly take a substance containing nitazenes.

Appearance, colour, smell and packaging cannot reliably establish what a drug contains. Nor can an ordinary drug screening test be assumed to detect every nitazene.

Can Drug Testing Detect Nitazenes?

Specialist laboratory analysis can identify nitazenes in drug samples, although the range of substances detected depends on the testing method used.

Nitazene-specific test strips are also available through some harm reduction services. However, their accuracy varies according to the nitazene involved, its concentration and the composition of the sample.

Importantly, a negative test-strip result does not guarantee that nitazenes are absent. Some compounds may not be detected, and testing cannot establish that an unknown drug is safe to consume.

Public Health Scotland provides further information on drug checking and the limitations of nitazene test strips.

Staying Safe

Staying informed about nitazenes and recognising the symptoms of an opioid overdose can save lives. Avoiding illicit and counterfeit drugs is the most reliable way to prevent exposure to unexpected synthetic opioids.

For people who continue to use drugs, harm reduction advice includes avoiding using alone, avoiding combinations with alcohol or other depressants, accessing drug checking services where available and ensuring that naloxone is accessible.

These measures can reduce some risks, but they cannot make nitazene use safe. Anyone concerned about their own or someone else’s drug use should seek advice from a healthcare professional or a local drug and alcohol support service.

The continuing presence of nitazenes in the UK drug supply makes awareness, effective overdose response and access to treatment particularly important.

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