Four main ingredients. FDA-approved carriers. UK banned substances excluded.

UK vape liquid contains four main components: propylene glycol (PG), vegetable glycerin (VG), nicotine plus food-grade flavourings. UK TPD regulations require ingredient listing, ban specific substances including diacetyl plus mandate quality standards. Most products use 50/50, 70/30 or 60/40 PG/VG ratios. Clean simple ingredient profiles are the standard. PG plus VG are both FDA-approved carriers used in medicines plus food for decades. Nicotine comes in freebase or salt form with 20mg/ml UK maximum. Flavourings are food-grade compounds meeting additional inhalation safety requirements. Here is the comprehensive breakdown of each ingredient plus UK regulatory framework. For the testing framework see our testing guide. This article is general consumer information, not medical advice.

Propylene glycol (PG)

What it is.

• Thin clear liquid.
• Slightly sweet taste.
• Chemical formula C3H8O2.
• FDA-approved food additive.
• Used in food, medicine, cosmetics for decades.

Role in vape liquid.

• Carrier for nicotine plus flavourings.
• Produces throat hit similar to cigarette.
• Thin viscosity for wicking in devices.
• Carries flavour compounds effectively.
• Vapour produced but less visible than VG.

Safety profile.

• Generally Recognized As Safe (GRAS) for oral consumption.
• Short-term inhalation safety well-established.
• Long-term chronic inhalation over decades less studied.
• Some individual sensitivity (dry mouth, throat irritation).
• Uncommon genuine allergies.

Typical concentration.

• 30-70 per cent of e-liquid depending on ratio.
• 50/50 products have equal PG and VG.
• 70/30 PG/VG high-PG blends.
• 30/70 PG/VG high-VG blends.

Pharmaceutical grade.

• Compliant UK products use pharmaceutical or USP (food) grade PG.
• Industrial grades not appropriate for vape.
• Quality impacts safety.

Vegetable glycerin (VG)

What it is.

• Thicker clear liquid.
• Slightly sweet taste.
• Chemical formula C3H8O3.
• FDA-approved food additive.
• Used in food, medicine, cosmetics widely.
• Plant-based (sourced from vegetable oils).

Role in vape liquid.

• Carrier alongside PG.
• Produces most of the visible vapour.
• Thicker viscosity.
• Milder throat hit than PG.
• Slightly sweeter effect.

Safety profile.

• Generally Recognized As Safe (GRAS).
• Short-term inhalation safety established.
• Long-term chronic inhalation less studied.
• Generally better tolerated than PG by sensitive users.
• Vegan and halal compatible.

Typical concentration.

• 30-70 per cent depending on ratio.
• Higher VG means bigger clouds.
• Higher VG means slower wicking (needs appropriate device).

Source.

• Derived from vegetable oils.
• Coconut, palm or soy typically.
• Generally considered plant-based.

Nicotine

Two main forms.

Freebase nicotine.

• Traditional form.
• Stronger throat hit.
• Higher pH (more alkaline).
• Common in 3, 6, 12mg strengths typically.
• Good for lower strength vaping.
• Harsh at higher strengths.

Nicotine salts.

• Nicotine combined with organic acid (often benzoic acid).
• Smoother hit at higher strengths.
• Lower pH (less alkaline).
• Common in 10, 15, 20mg strengths.
• Allows higher strength without harshness.
• Closer to cigarette nicotine delivery profile.
• Our full range covers every UK legal strength.

UK limits.

• Maximum 20mg/ml nicotine strength.
• 0mg (nicotine-free) options also available.
• Strengths below 20mg: typically 3, 6, 10, 12, 15, 18mg.
• Applies to both freebase and salt forms.

Source.

• Derived from tobacco plant.
• Also synthetically produced increasingly.
• Pharmaceutical-grade nicotine required for compliant products.

Flavourings

Food-grade compounds.

• Broadly similar to food industry flavourings.
• Must meet additional inhalation safety standards.
• UK TPD bans specific problematic compounds.

Main categories.

• Fruit flavours: most popular category (berry, citrus, tropical, apple, etc).
• Tobacco flavours: traditional, favoured by ex-smokers.
• Mint plus menthol: cooling sensation, often blended.
• Dessert plus bakery: vanilla, cake, pastry notes.
• Beverages: coffee, cola, energy drinks.
• Candy: sweet fruit plus confectionery notes.

UK TPD banned substances.

• Diacetyl (banned May 2016). Associated with popcorn lung. Major safety measure.
• Acetyl propionyl (similar concerns, banned).
• CMR substances (carcinogenic, mutagenic, reproductive toxic) banned.
• Caffeine, taurine, vitamins as vape additives banned.
• Certain colouring agents banned.

Concentration.

• Typically 5-15 per cent of total volume.
• Complex flavours have more components.
• Simpler flavours often considered better quality.

Water and other minor components

Water.

• Small amounts sometimes added.
• Adjusts viscosity plus dilution.
• Not primary component typically.

Cooling agents (optional).

• WS-23, menthol, koolada for menthol effect without minty taste.
• Legal in UK when compliant.

Alcohol (rare).

• Small amounts sometimes used as solvent for specific flavours.
• Ethanol mostly. Usually not listed if under 1 per cent.

Sweeteners (vape-specific).

• Sucralose plus ethyl maltol sometimes used.
• Controversial as they may contribute to coil gunking plus possibly inhalation effects.
• UK TPD allows but some premium brands avoid.

PG/VG ratios explained

50/50 (equal parts).

• Balanced throat hit plus vapour.
• Suits most beginner devices including pod systems.
• Wicks well in most tanks.
• Most nicotine salts are 50/50.
• Most common for new vapers.

70/30 (PG heavy).

• Stronger throat hit.
• Less vapour.
• Wicks very easily.
• Less common now.

70/30 or 60/40 (VG heavy).

• Smooth hit.
• More vapour plus clouds.
• Needs appropriate device (sub-ohm typically).
• Common for DTL (direct-to-lung) vaping.
• Common for shortfills (0mg bases you add nicotine to).

Max VG (80/20 or higher VG).

• Maximum clouds.
• Very smooth.
• Needs high-performance device.
• Specialist cloud-chasing use.

How to read e-liquid labels

UK TPD-compliant products must display:

• Ingredient list showing all components.
• Nicotine strength in mg/ml (0-20mg/ml UK legal).
• PG/VG ratio usually shown as percentage.
• Bottle size (10ml UK maximum for nicotine products).
• MHRA registration number.
• Batch number.
• Expiry or best-before date.
• Warning labels required by law.
• Child-resistant cap (TPD requirement).
• Manufacturer plus importer details.

These all indicate UK compliance. Absence of these markers suggests non-compliant product with no safety testing guarantees.

Quality indicators

Signs of quality e-liquid:

• UK TPD compliant with proper labelling.
• MHRA registration displayed.
• Pharmaceutical or food grade ingredients stated.
• Clear bottle allowing visual inspection.
• Natural colour (most should be clear or pale yellow).
• Transparent ingredient disclosure.
• Reputable manufacturer.
• Proper child-resistant packaging.
• Batch testing information available.

Warning signs to avoid:

• No MHRA registration.
• No ingredient disclosure.
• No manufacturer details.
• Unusual colour or appearance.
• Very cheap pricing that seems too good.
• Imports without UK compliance labelling.
• Non-child-resistant packaging.
• Obvious knock-off branding.

What is NOT in UK compliant vape liquid

Explicitly banned by UK TPD:

• Diacetyl (popcorn lung risk).
• Acetyl propionyl.
• CMR substances (carcinogenic, mutagenic, reproductive toxic).
• Caffeine.
• Taurine.
• Vitamins added as functional ingredients.
• Certain colouring agents.
• THC or other controlled drugs.
• Vitamin E acetate (linked to EVALI).

Compliant products exclude these. Black market or non-compliant products may contain these without user knowledge.

Comparing vape ingredients to cigarettes

Cigarette smoke contents:

• Over 7,000 chemicals produced through combustion.
• Over 70 known carcinogens.
• Tar (over 40 known carcinogens).
• Carbon monoxide.
• Polycyclic aromatic hydrocarbons.
• Nitrosamines.
• Heavy metals (cadmium, arsenic, lead).
• Radioactive compounds.
• Many irritants and toxins.

Vape contents:

• Four main ingredients (PG, VG, nicotine, flavours).
• Small additional compounds.
• Some thermal breakdown products during heating.
• Orders of magnitude simpler than smoke.
• Most smoking-related harmful compounds absent.

This simpler ingredient profile is the foundation of why vape is substantially less harmful than smoking.

Practical approach

• Four main ingredients: PG, VG, nicotine, flavourings.
• PG plus VG are FDA-approved carriers used in food plus medicine for decades.
• Nicotine in freebase or salt form. 20mg/ml UK maximum.
• Flavourings meet food-grade plus inhalation safety standards.
• UK TPD bans specific compounds including diacetyl since 2016.
• Much simpler than cigarette smoke which has over 7,000 chemicals.

For UK TPD-compliant products with full ingredient disclosure, our nicotine salts collection features every UK compliant strength from 20mg down to 3mg with clear labelling plus MHRA registration.

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