Why the base matters as much as the label

If you live with eczema, psoriasis, rosacea or just skin that flares and stings at the drop of a hat, you have probably been told to "moisturise more". That advice is sound, but it is incomplete. The type of moisturiser you choose matters enormously, because a product that suits someone else's skin can leave yours burning within minutes.

In the UK, medical moisturisers are usually called emollients. They come as lotions, creams, ointments, gels and sprays. The active ingredients are often similar; what changes is the ratio of oil to water, and that single difference decides how a product feels, how long it lasts and how likely it is to sting. Understanding the three main formats makes choosing far less of a lottery.

Lotions: light, cooling and often not enough

Lotions are mostly water with a little oil, which makes them thin, easy to spread and pleasant on hairy areas such as the scalp, chest and legs. They are useful for daytime use when you want to get dressed quickly, and they feel cooling on hot, itchy skin.

The downside is staying power. High water content means lotions evaporate quickly, so they need frequent reapplication, sometimes several times a day. Many also contain alcohol or preservatives that sting sharply on cracked or excoriated skin. If your skin is genuinely dry and sensitive rather than just mildly thirsty, a lotion is usually the wrong first choice.

Creams: the everyday middle ground

Creams are emulsions of oil and water, thicker than lotions but still easy to rub in. They absorb reasonably fast, leave less residue, and suit most areas of the body. For many people with dry, sensitive skin, a good cream is the practical default for daytime use.

Bear in mind that because creams contain water, they need preservatives to stop bacteria and mould growing in the tub. Common ones include phenoxyethanol and parabens. Most people tolerate these perfectly well, but if a cream reliably stings on contact, it is often the preservative rather than the emollient itself. Look for a preservative-free cream, frequently sold in airless pump dispensers, or step up to an ointment. Creams are also the format most likely to contain fragrance, so check the ingredient list carefully.

Ointments: the heaviest, and often the kindest

Ointments contain little or no water. They are thick, occlusive and stay on the skin for hours, forming a barrier that reduces water loss and protects against irritants. Because there is no water in them, they need no preservatives, which is a real advantage for sensitive skin.

They are the most effective choice for very dry, cracked or thickened skin, and they are ideal for overnight use on hands, feet, elbows, knees and the body. The trade-offs are obvious: they feel greasy, can mark bedding and clothing, and may feel uncomfortably warm in summer. Avoid heavy ointments on weeping, oozing or infected skin, and think twice before using them on the face during the day. If you find a pure ointment too heavy, a fifty-fifty blend with a cream can be a good compromise.

Ingredients worth seeking out, and ones to avoid

Once you have settled on a format, scan the label.

• Helpful: glycerine, petrolatum, liquid and white soft paraffin, ceramides, shea butter, colloidal oatmeal, and urea in low concentrations for thickened skin.
• Avoid where possible: added fragrance, essential oils, menthol, camphor, alcohol denat., and harsh surfactants such as sodium lauryl sulfate.
• Approach with care: lanolin, which is an excellent emollient but a known allergen for a small number of people, and urea or lactic acid, which sting badly on broken skin even though they are brilliant on intact, scaly areas.
• Patch test: apply a small amount to the inner forearm and leave it for 48 hours before using it widely.

Putting it together: a routine that actually works

Aim to apply emollient within three minutes of washing, while the skin is still damp, to trap moisture in. Smooth it on in the direction of hair growth rather than rubbing vigorously, and use generous amounts. Many adults with widespread dry skin need 500g or more a month, so do not be timid.

• Use a lotion for hairy areas and quick daytime top-ups.
• Use a cream as your everyday moisturiser for most of the body.
• Use an ointment at night, on very dry patches, and on hands after washing.
• Decant from tubs with a clean spoon, or choose a pump, to avoid introducing bacteria.
• Keep going when your skin is calm. Emollients prevent flares; they are not just for bad days.

If you are also using a prescribed topical steroid, leave around 20 to 30 minutes between the two products, and follow the order your GP or pharmacist advised. Moisturisers support treatment but do not replace it. Finally, if your skin is broken, weeping, hot or increasingly painful, or if a product stings every time you use it, stop and speak to your pharmacist or GP. Finding the right emollient is often a matter of trial and error, and there is no shame in working through a few before you find your match.