Ointments, creams, lotions and gels are the same idea at four different water-to-oil ratios, and that ratio is what decides how each behaves on eczema-prone skin. An ointment is close to pure lipid, so it seals hard and needs no preservative. A cream or a gel is mostly water, held together by an emulsifier or a gelling agent, so it spreads further, sinks in faster and carries a preservative that some skin objects to.
Two UK facts sit behind the choice and appear nowhere on the packaging. NICE tells prescribers to issue 250 g to 500 g of leave-on emollient a week, which is far more than most people get through. And the fire warning the MHRA issued covers every emollient sold here, paraffin-based or not.
What the four formats are actually made of
Three licensed products make useful reference points, because their summaries of product characteristics list exactly what is in them. Emulsifying Ointment BP is emulsifying wax 30%, white soft paraffin 50% and liquid paraffin 20%. Its list of excipients reads "None used". There is no water in it, so there is nothing to preserve.
Aqueous Cream BP is built from that same ointment, diluted. Its composition is emulsifying ointment 30% w/w, of which white soft paraffin 15% w/w and liquid paraffin 6.0% w/w, with purified water among the excipients and phenoxyethanol 1% w/w holding it stable.
Doublebase Gel takes a third route to the same job. The oily part is isopropyl myristate 15% w/w and liquid paraffin 15% w/w, and the remainder is purified water thickened with carbomer and preserved with phenoxyethanol. Its SmPC describes those oily ingredients as forming "an occlusive barrier" that reduces "drying from evaporation".
That is the whole axis: how much of the pack is lipid, and what holds the rest together. A lotion sits at the thin end, which is why the NHS calls lotions "not very moisturising" while listing them as "good for hairy or damaged areas of skin". Sprays sit outside the ranking. The NHS puts them as "good for hard-to-reach areas and sore or infected skin", and they are the only format that goes on without pressing on the skin. Which format suits which time of day is set out in how to moisturise eczema.
Water in the tub means preservative in the tub
Aqueous Cream BP is the cautionary example, and a UK-specific one. Its own SmPC warns that it "may be associated with immediate cutaneous reactions when used as a leave-on emollient, such as stinging, burning, itching and redness". It names sodium lauryl sulfate at 0.9% w/w as an ingredient that "may cause local skin reactions (e.g. stinging and contact dermatitis), particularly in children with atopic eczema".
Greasy does not automatically mean bland, though. Emulsifying Ointment BP carries the same sodium lauryl sulfate warning, because emulsifying wax is where that surfactant comes from. Water-free is not a synonym for surfactant-free, so the composition section is worth more than the format name on the front. What sits in the lipid phase is a separate question again, and ceramides and eczema covers the mixture of ceramides, cholesterol and fatty acids.
The quantity the guideline expects
NICE recommendation 1.5.1.4 in CG57 is addressed to prescribers, not patients: "Offer children with atopic eczema a choice of unperfumed emollients to use every day for moisturising. This may be a combination of products or one product for all purposes. Prescribe large quantities of leave-on emollients (250 g to 500 g weekly) that are easily available to use at nursery, pre-school or school."
Two qualifications belong with that number. CG57 is titled Atopic eczema in under 12s, so the figure was set for children rather than adults. And it is a supply instruction, so it describes what should be issued, not a dose to be measured out. The same guideline calls emollients "the basis of management" that "should always be used, even when atopic eczema is clear" at 1.5.1.1, and says at 1.5.1.5 that they should be used "in larger amounts and more often than other treatments".
What that volume does to a shortlist is the useful part. At hundreds of grams a week, price per 100 g and the largest pack a product comes in stop being trivia. So does the wording: a combination of products is explicitly allowed, so splitting the week's quantity across two formats is a valid answer rather than a compromise. How to moisturise eczema works the weekly figure back to an amount per application.
Pump, tub or tube
The NHS advice for anything sold in a pot is short: "Use a clean spoon or spatula to remove emollients from a pot or tub." The British Association of Dermatologists gives the full sequence and the reason. Take out what you need with a spoon or spatula, put it on a piece of kitchen roll, then apply from there, because "This stops bacteria from getting into the container and contaminating it". The consequence it names is direct: "Contaminated moisturiser can be a source of infection, which will then transfer back onto your skin."
A pump dispenser removes that step instead of adding a rule to remember, which is the argument for buying the same product in a pump where the manufacturer offers one. At 250 g to 500 g a week the container is opened many times, and each of those is an occasion for the spoon to be missing.
The fire risk covers every emollient, not just paraffin ones
The MHRA's Drug Safety Update on emollients and burns, published 26 August 2020 and last updated 20 May 2021, is unambiguous on scope: "This applies to all emollients, whether they contain paraffin or not."
The mechanism is fabric, not skin. "Emollients can transfer from the skin onto clothing, bedding, dressings, and other fabric. Once there, they can dry onto the fabric and build up over time. In the presence of a naked flame, fabric with emollient dried on is easily ignited."
The scale came from the MHRA's earlier update of 18 December 2018. It reported "50 fire incidents (49 fatal) reported by Fire and Rescue Services" in England between 2010 and November 2018, and separately 11 cases, five of them Coroner's Regulation 28 reports to Prevent Future Deaths, in which paraffin-based emollients were suspected of contributing to fatal burns. That update also stated that "Data suggest there is also a risk for paraffin-free emollients", because "paraffin-free products also have a fire accelerant effect in tests when emollient residue builds up on fabric". Laundry does not undo it: washing at a high temperature "may reduce emollient build-up but not totally remove it".
The warning sits on the products too. Emulsifying Ointment BP and Doublebase Gel, one water-free and one water-based, carry the identical line: "Fabric (clothing, bedding, dressings etc) that has been in contact with this product burns more easily and is a serious fire hazard." The NHS states the rule for the person using it: "Keep away from fire, flames and cigarettes when using all types of emollients (both paraffin-based and paraffin-free)."
Because it applies to all of them, this does not narrow the shortlist. It changes the household routine instead, for anyone who smokes, uses a gas hob, or sits close to an open fire or a heater.
Choosing one you will keep using
Both national bodies land in the same place on selection. The British Association of Dermatologists puts it as "The best moisturiser is the one you are happy to use regularly", alongside the flat statement that "Keeping the skin moisturised is one of the most important parts of eczema care". The NHS is equally plain that "You may have to try a few different emollients".
That is not a shrug. It sets the test a product has to pass: whether you can get through guideline quantities of it, week after week, without dreading it. Texture and how it feels under clothes are what decide that, and where a product stings on skin that is not broken, the composition section is the place to look. When you apply it carries as much weight as which one you buy, and the window straight after washing is covered in the bath and shower routine. If eczema stays uncontrolled on a routine already running at these quantities, that is a conversation with a GP or a dermatology service rather than another tub.
References
- NICE. Atopic eczema in under 12s: diagnosis and management (CG57). https://www.ncbi.nlm.nih.gov/books/NBK571009/
- MHRA. Emollients and risk of severe and fatal burns: new resources available. Drug Safety Update, published 26 August 2020, updated 20 May 2021. https://www.gov.uk/drug-safety-update/emollients-and-risk-of-severe-and-fatal-burns-new-resources-available
- MHRA. Emollients: new information about risk of severe and fatal burns with paraffin-containing and paraffin-free emollients. Drug Safety Update, 18 December 2018. https://www.gov.uk/drug-safety-update/emollients-new-information-about-risk-of-severe-and-fatal-burns-with-paraffin-containing-and-paraffin-free-emollients
- British Association of Dermatologists. Atopic eczema, patient information leaflet. https://www.bad.org.uk/pils/atopic-eczema
- NHS. Emollients, reviewed 24 October 2023. https://www.nhs.uk/conditions/emollients/
- Electronic Medicines Compendium. Emulsifying Ointment BP, summary of product characteristics. https://www.medicines.org.uk/emc/product/4571/smpc
- Electronic Medicines Compendium. Aqueous Cream BP, summary of product characteristics. https://www.medicines.org.uk/emc/product/4820/smpc
- Electronic Medicines Compendium. Doublebase Gel, summary of product characteristics. https://www.medicines.org.uk/emc/product/1325/smpc