Every system affected. Brain addiction central. Much less harmful than smoking.

Nicotine binds to nicotinic acetylcholine receptors throughout the body producing widespread effects across every major system. Brain effects include dopamine release, cognitive effects plus addiction mechanism. Cardiovascular effects include heart rate elevation (5-20 bpm), blood pressure rise (5-10 mmHg) plus vasoconstriction. Hormonal effects include cortisol plus adrenaline release. Metabolic effects include appetite suppression plus small metabolic rate increase. Plus effects on respiratory system, gastrointestinal tract, skin, oral tissues plus reproductive system. Effects peak 10-30 minutes after dose plus decline over 1-2 hours. Here is the comprehensive body-systems tour of what nicotine actually does. For the specific stimulant classification see our stimulant guide. This article is general consumer information, not medical advice.

How nicotine enters the body

Absorption routes plus speeds vary significantly:

Inhalation (vape, cigarettes).

• Fastest route. Lung surface area enormous.
• 10-20 seconds from puff to brain.
• Sharp peaks plus rapid declines.
• Highly reinforcing due to speed.
• Main driver of addiction potency.

Oral (NRT gum, lozenges).

• Buccal absorption through mouth lining.
• 10-30 minutes to effective levels.
• Slower peaks, more gradual decline.
• Less reinforcing than inhalation.
• Appropriate for cessation support.

Transdermal (NRT patches).

• Slowest route. Skin absorption.
• Steady delivery over 16-24 hours.
• No peaks or craving-triggering decline patterns.
• Lowest reinforcement potential.
• Well-suited for cessation.

Nasal plus sublingual (less common).

• Faster than patches.
• Specific clinical contexts.

Speed matters: rapid delivery creates stronger reinforcement plus addiction potential. This is why vape plus cigarettes are more addictive than NRT despite delivering similar nicotine amounts.

Brain and nervous system

Nicotine affects the central nervous system extensively:

Receptor binding.

• Binds nicotinic acetylcholine receptors (nAChRs) throughout brain.
• Multiple receptor subtypes with different effects.
• Competitive with natural acetylcholine.
• Widespread brain regions affected.

Dopamine release.

• Activates ventral tegmental area.
• Dopamine release in nucleus accumbens.
• Creates reward signal.
• Drives reinforcement plus addiction.
• Foundation of nicotine dependence.

Cognitive effects.

• Modest attention enhancement.
• Some working memory effects.
• Faster reaction times in specific tests.
• Subjective mental clarity.
• Much is withdrawal relief in regular users.

Mood effects.

• Mild anxiolytic effects at moderate doses.
• Associated with depression in long-term users.
• Complex relationship with mental health.
• Withdrawal-anxiety cycles in dependent users.

Developing brain (minors).

• Brain develops into mid-20s.
• Effects on attention, learning, impulse control.
• Stronger lifetime dependence if early exposure.
• Major concern behind UK 18+ age restriction.

Long-term changes.

• Receptor upregulation from chronic use.
• More receptors compensating for tolerance.
• Physical dependence based on these changes.
• Takes weeks to normalise after cessation.

Cardiovascular system

Nicotine produces clear cardiovascular effects:

Heart rate.

• Increases 5-20 beats per minute.
• Peak 10-30 minutes after dose.
• Declines over 1-2 hours.
• Sympathetic nervous system activation.

Blood pressure.

• Rises 5-10 mmHg (both systolic plus diastolic).
• Vasoconstriction of peripheral vessels.
• Adrenaline release contributes.
• Chronic elevation in heavy users.

Vascular effects.

• Endothelial function affected.
• Reduced nitric oxide production.
• Impaired vasodilation.
• Reduced peripheral circulation.

Heart workload.

• Increased cardiac workload.
• Higher oxygen demand.
• More concerning with existing heart disease.
• Chronic effects may contribute to cardiovascular risk.

Compared to smoking.

• Nicotine cardiovascular effects real but substantially less than smoking.
• Smoking adds CO plus combustion-driven inflammation.
• Most smoking cardiovascular harm from non-nicotine components.

Respiratory system

Airway effects.

• Some bronchial smooth muscle effects.
• Can trigger bronchoconstriction in susceptible individuals.
• Airway irritation in new users often resolves.
• Increased respiratory rate.

Specific vape respiratory effects.

• PG can cause dry mouth plus throat.
• VG contributes to vapour production.
• Different from combustion respiratory effects.
• Less severe than smoking respiratory impact.

Compared with smoking.

• Smoking causes COPD, lung cancer, chronic bronchitis.
• Nicotine alone does not cause these at smoking rates.
• Combustion products drive most smoking respiratory harm.

Hormonal system

Nicotine significantly affects hormones:

Adrenaline (epinephrine).

• Triggers release from adrenal medulla.
• Part of “fight or flight” response.
• Contributes to heart rate plus BP effects.
• Each vape session produces adrenaline pulse.

Cortisol.

• Stress hormone.
• Released with nicotine.
• Chronic use flattens daily rhythm.
• May contribute to fatigue plus mood effects.

Insulin plus blood sugar.

• Effects on insulin sensitivity.
• Can affect blood sugar regulation.
• Relevant particularly with diabetes.

Thyroid.

• Modest effects on thyroid function.
• Not major clinical concern for most.

Reproductive hormones.

• Can affect testosterone modestly in men.
• Effects on female reproductive hormones.
• During pregnancy affects placental function plus foetal development.
• Fertility effects documented.

Metabolic system

Appetite.

• Nicotine suppresses appetite.
• Effect on hypothalamic feeding centres.
• Can affect eating patterns.
• Quitting typically produces 5-10 lb weight gain.

Metabolic rate.

• Small increase (2-10 per cent).
• Contributes to weight effects.
• Not clinically significant for weight management.

Fat metabolism.

• Some effects on lipolysis.
• Minor clinical significance.

Body temperature.

• Slight increase during acute effects.
• Part of stimulant response.

Gastrointestinal system

Motility.

• Increased gut motility.
• Can affect bowel habits.
• Why some users find vape affects bowel patterns.

Specific conditions.

• Ulcerative colitis: some evidence of benefit from nicotine.
• Crohn disease: worse with smoking, less clear with vape.
• IBS: effects vary individually.
• Reflux: nicotine can worsen in some users.

Liver metabolism.

• Nicotine metabolised mainly in liver.
• CYP2A6 enzyme primary pathway.
• Genetic variation affects metabolism speed.
• Affects medication metabolism in some cases.

Oral plus dental effects

Saliva.

• Dry mouth common.
• Reduced saliva production.
• PG contributes additionally.

Gums.

• Vasoconstriction reduces gum blood flow.
• Some effects on gum tissue.
• Less severe than smoking gum effects.

Teeth.

• Mild staining effects.
• Reduced saliva contributes to cavities.
• Much less severe than smoking tooth effects.

Oral tissue.

• Some effects on mucosa.
• Persistent sores warrant dental or GP review.

Skin effects

Vasoconstriction.

• Reduces skin blood flow.
• Over time may affect skin appearance.
• Less severe than smoking skin effects.

Wound healing.

• Nicotine impairs wound healing.
• Why surgeons recommend pre-surgery cessation.
• Also affects healing from injuries.

Skin aging.

• Chronic vasoconstriction may contribute.
• Much less than smoking wrinkle effects.

Reproductive system

Male reproductive.

• Sperm quality effects.
• Erectile function affected over time.
• Testosterone mild effects.
• Our fertility guide covers this.

Female reproductive.

• Menstrual cycle effects in some users.
• Fertility may be affected.

Pregnancy.

• Reduced placental blood flow.
• Foetal development effects.
• Low birth weight risk.
• NHS: stop during pregnancy where possible.

Immune system

Complex effects.

• Some immunomodulation.
• Effects on inflammation not fully understood.
• Possibly reduced antibody response.
• Generally modest compared to smoking immune effects.

How nicotine leaves the body

Metabolism.

• Mainly in liver via CYP2A6 enzymes.
• Cotinine is main metabolite.
• Further metabolites excreted by kidneys.
• Individual variation in metabolism speed.

Half-life.

• Approximately 2 hours in blood.
• Ranges 1-4 hours by genetics plus other factors.
• Cotinine half-life 15-40 hours.
• Cotinine used as detection marker in tests.

Full clearance.

• Nicotine itself clears blood within 24-48 hours.
• Cotinine detectable 1-3 days typically.
• Urine tests sensitive for several days.
• Receptor-level changes take weeks to normalise.

Putting it all together

Nicotine is not a subtle drug. It produces measurable effects across essentially every body system. Most effects are moderate in magnitude at typical doses but add up to significant physiological impact. Addiction is the main negative. Cardiovascular effects matter for long-term health. Developmental effects matter for minors. Pregnancy effects matter for foetal development.

Importantly: nicotine itself is much less harmful than smoking. Smoking adds combustion products (tar, CO, thousands of chemicals) that cause most smoking disease. Nicotine alone produces relatively limited direct disease compared to smoking.

Practical approach

• Nicotine affects every body system. Not a subtle drug.
• Brain addiction is main effect. Dopamine-driven reinforcement.
• Cardiovascular effects significant. Particularly with existing conditions.
• Much less harmful than smoking because no combustion products.
• Effects mostly reversible after cessation over weeks to months.
• Developing brains and foetuses most vulnerable.

For those managing nicotine exposure through strength step-down, our nicotine salts collection covers every UK compliant strength from 20mg down to 3mg.

For the wider view on vape, nicotine effects plus health questions, our full health hub covers every major question UK readers ask.