What is it?
NPS is an umbrella term for chemicals designed to produce effects similar to established drugs. Content and strength are frequently unknown, and different batches can behave very differently.
Common forms
- Powders
- Tablets
- Herbal blends
- Liquids and vapes
How it affects the body
Effects depend entirely on the chemical involved — some act like stimulants, some like sedatives, some like cannabinoids or hallucinogens.
Short-term effects
- Highly variable and unpredictable effects
- Severe agitation or sedation
- Nausea and confusion
Long-term effects
- Poorly characterised — long-term effects are often unknown
- Dependence with some substances
- Mental-health difficulties
Dependence and addiction
Dependence can develop when the body and brain adapt to regular use. It is not a moral failing or a lack of willpower. Signs people describe include needing more to get the same effect, difficulty cutting down, spending more time thinking about use, and continuing despite harm. Support is available at any stage — you do not need to have reached a crisis point.
Withdrawal
Stopping or reducing after regular use can cause withdrawal. Withdrawal varies between people and depends on how much and how long someone has used, their physical health and other substances involved. Some withdrawal can be medically serious, so it is safer to plan a reduction with a clinician or a drug and alcohol service rather than stopping abruptly alone.
Overdose risks
Because strength is unpredictable, emergencies can happen quickly. Call 999 for unresponsiveness, seizures, severe agitation or breathing difficulty, and tell clinicians everything that was taken.
Mixing substances
Mixing with anything else compounds unpredictability. Synthetic opioids may be present without the person's knowledge — naloxone can be relevant.
Harm-reduction information
- Assume strength and content are unknown
- Avoid using alone
- Consider naloxone where synthetic opioids may be present
- Local drug-checking or harm-reduction services can advise on current risks and alerts
When to seek urgent medical help
Call 999 if someone is unconscious or cannot be woken, is having difficulty breathing, has a seizure, has chest pain, becomes very confused or agitated, or you are worried they may have overdosed. For urgent advice that is not life-threatening, call NHS 111. You will not get someone into trouble by calling for medical help.
Treatment and recovery options
- Talking therapies and structured psychosocial support
- Community drug and alcohol services, including self-referral where available
- Medication-assisted treatment where clinically appropriate
- Medically supported withdrawal, arranged and monitored by clinicians
- Peer support and recovery communities
- Residential rehabilitation for some people, usually via assessment
- Support for related needs — mental health, housing, family and welfare
UK support resources
- NHS — health information and service finders (nhs.uk)
- Talk to FRANK — UK drug information service (talktofrank.com)
- Your local community drug and alcohol service — many accept self-referrals
- Local pharmacy teams, who can offer advice and signposting
Sources / references
This page is a plain-language summary written for education. For clinical or legal detail, use authoritative UK sources: NHS (nhs.uk), Talk to FRANK (talktofrank.com), NICE (nice.org.uk), UK Government and devolved government publications, and guidance from UK professional bodies. Each page on this site carries a review date, and we welcome corrections.