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Substances and their Effects
26th September 2025
Substances and their effects
Information about the short and long-term effects of common substances, including harm reduction tips and signs of problematic use.
This information can be downloaded as a PDF here.
The substances included on this page are:
– Alcohol – Take me there
– Cannabis (smoked / edible) – Take me there
– THC Vapes – Take me there
– Cocaine – Take me there
– Ketamine – Take me there
– Solvents (glue, aerosols, nitrous oxide) – Take me there
– Nitrous Oxide (NOS / Whippets) – Take me there
– MDMA (Ecstasy) – Take me there
– Illicit Prescription Drugs (Benzos) – Take me there
Alcohol
Short-term effects
– Lowered inhibitions
– Slurred speech
– Poor coordination
– Risky behaviour
Long-term effects
– Liver disease
– Dependency
– Depression
– Brain / heart damage
Signs of problematic use
– Binge drinking
– Blackouts
– Aggression
– Neglect of responsibilities
– Mood swings
– Depression
– Anxiety
Harm reduction tips
– Alternate alcoholic and non-alcoholic drinks
– Eat before / while drinking
Overdose risks
– Alcohol poisoning (vomiting, unconsciousness, slow / irregular breathing, death)
Do not mix with
– Benzos
– Opioids
– Ketamine
– GHB
Effects on the body
– Depresses nervous system
– Slows reflexes / breathing
– Irritates stomach lining
– Damages liver / heart
Cannabis (smoked / edible)
Short-term effects
– Relaxation
– Altered perception
– Slowed reaction
– Increased appetite
Long-term effects
– Dependency
– Reduced motivation
– Anxiety
– Psychosis risk
Signs of problematic use
– Smell on clothes
– Red eyes
– Secrecy
– Poor performance
– Paranoia
– Anxiety
– Low mood
– Loss of motivation
Harm reduction tips
– Avoid mixing with tobacco
– Choose lower-strength strains
Overdose risks
– No fatal overdose
– Very high doses > panic, vomiting, hallucinations
Do not mix with
– Alcohol
– Stimulants
– Hallucinogens
Effects on the body
– Increases heart rate
– Impairs memory and coordination
– Affects mood / motivation circuits in brain
THC Vapes
Short-term effects
– Relaxation
– Altered perception
– Dry mouth
– Red eyes
– Rapid heartbeat
Long-term effects
– Dependency
– Lung irritation
– Anxiety / paranoia
– Memory issues
Signs of problematic use
– Frequent vaping
– Secrecy
– Red eyes
– Poor performance
– Low mood
– Anxiety
– Paranoia
– Social withdrawal
Harm reduction tips
– Avoid high-potency cartridges
– Don’t share devices
Overdose risks
– High doses > anxiety, paranoia, nausea
Do not mix with
– Alcohol
– Stimulants
– Hallucinogens
Effects on the body
– Delivers THC quickly to bloodstream
– Raises heart rate
– Irritates lungs
– Alters brain chemistry
Cocaine
Short-term effects
– Euphoria
– Energy
– Confidence
– Talkativeness
– Reduced appetite
Long-term effects
– Nasal damage
– Heart disease
– Paranoia
– Depression
– Dependency
Signs of problematic use
– Nosebleeds
– Mood swings
– Financial issues
– Agitation
– Paranoia
– Anxiety
– Irritability
– Comedown depression
Harm reduction tips
– Don’t share snorting equipment
– Take breaks between use
Overdose risks
– Heart attack
– Stroke
– Seizures
– Overheating
– Sudden death
Do not mix with
– Alcohol (forms toxic cocaethylene in the liver)
– Opioids
– Other stimulants
Effects on the body
– Constricts blood vessels
– Raises blood pressure / heart rate
– Overstimulates reward system
– Strains cardiovascular system
Ketamine
Short-term effects
– Dissociation
– Dream-like state
– Loss of coordination
– Slurred speech
Long-term effects
– Bladder / kidney damage
– Memory issues
– Dependency
Signs of problematic use
– Stumbling walk
– Slurred speech
– Frequent toilet use
– Depression
– Confusion
– Emotional blunting
Harm reduction tips
– Use in safe spaces
– Avoid mixing with alcohol
Overdose risks
– Unconsciousness
– Slowed breathing
– Choking
– Paralysis
Do not mix with
– Alcohol
– Opioids
– Benzos
Effects on the body
– Depresses nervous system
– Numbs pain signals
– Damages bladder lining
Find out more about ketamine in our Understanding Ketamine resource, here.
Solvents (glue, aerosols, nitrous oxide)
Short-term effects
– Euphoria
– Dizziness
– Hallucinations
– Poor coordination
Long-term effects
– Brain / nervous system damage
– Liver / kidney damage
– Sudden sniffing death
Signs of problematic use
– Chemical smell
– Stains around mouth / nose
– Dazed behaviour
– Mood swings
– Confusion
– Memory problems
Harm reduction tips
– Ventilated spaces
– Never alone
– Avoid flames
Overdose risks
– Suffocation
– Heart failure
– Seizures
– Unconsciousness
– Death
Do not mix with
– Alcohol
– Depressants
– Other inhalants
Effects on the body
– Displaces oxygen in lungs
– Damages nerves / organs
– Affects heart rhythm
Nitrous Oxide (NOS / Whippets)
Short-term effects
– Euphoria
– Giggling
– Light-headedness
– Numbness
Long-term effects
– B12 deficiency
– Nerve damage
– Memory loss
– Brain damage (heavy use)
Signs of problematic use
– Empty canisters
– Slurred speech
– Unsteady walk
– Anxiety
– Mood swings
– Confusion
– Depression with heavy use
Harm reduction tips
– Use in ventilated areas
– Never directly from canister
– Sit down while using
Overdose risks
– Hypoxia
– Fainting
– Accidents
– Heart failure
Do not mix with
– Alcohol
– Depressants
– Solvents
Effects on the body
– Reduced brain oxygen
– Damages nerves with prolonged use
– Affects cardiovascular / nervous system
MDMA (Ecstasy)
Short-term effects
– Euphoria
– Empathy
– Sensory enhancement
– Jaw clenching
– Sweating
Long-term effects
– Memory problems
– Depression
– Sleep disturbance
– Serotonin damage
Signs of problematic use
– Dilated pupils
– Jaw clenching
– Low mood after use
– Anxiety
– Depression
– Irritability during comedown
Harm reduction tips
– Sip water (not too much)
– Take breaks from dancing
Overdose risks
– Overheating
– Dehydration
– Water intoxication
– Seizures
– Heart failure
Do not mix with
Stimulants | SSRIs / MAOIs | alcohol
Effects on the body
Floods brain with serotonin / dopamine | raises heart rate / temperature | depletes brain chemicals
Illicit Prescription Drugs (Benzos)
Short-term effects
– Relaxation
– Drowsiness
– Reduced anxiety
– Memory gaps
Long-term effects
– Dependence
– Overdose risk
– Cognitive decline
Signs of problematic use
– Confusion
– Excessive sleep
– Hidden packs
– Depression
– Anxiety
– Emotional instability
– Irritability
Harm reduction tips
– Never mix with alcohol / depressants
– Taper off with medical support
Overdose risks
– Slowed breathing
– Coma
– Death (especially with alcohol / opioids)
Do not mix with
– Alcohol
– Opioids
– Ketamine
– GHB
Effects on the body
– Slows brain / nervous system
– Relaxes muscles
– Suppresses breathing
– Impairs memory
More information about substances
– Drugwise – Promoting evidence-based information on drugs, alcohol and tobacco – Click here
– Drugs and Me – Guides, blogs, digital tools and research to help people manage their drug use – Click here
– Drug Science – Knowledge and resources about drugs to create positive change – Click here
Do you want support with your substance use?
The DASH team at No Limits can help you to manage your alcohol use and they will be flexible to what your needs are.
They will give you information, advice and support around your alcohol use and help you create a plan to cut down and help you change your habits by getting you involved in a range of activities.
Who is DASH for?
DASH is for anyone under 25 living in Southampton postcodes SO14-SO19. If you are over our age limit but live in SO14-SO19, go to Change Grow Live for support. If you are outside of our area, our team can help with signposting you to your local service.
How do I get support from DASH?
– Drop in to our Advice Centre
– Refer online through our website
– Call 02380 224 224 (option 2)
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