An ointment is a semi-solid topical preparation that contains a high proportion of oil or fat and very little water. This greasy consistency is what separates ointments from creams, lotions, and gels, and it’s also what makes them especially effective at locking moisture into the skin. If you’ve ever used petroleum jelly, you’ve used one of the simplest ointments available.
How Ointments Work on Your Skin
Your skin’s outermost layer, the stratum corneum, acts as a two-way barrier. It keeps water and electrolytes inside your body while blocking harmful substances from getting in. When this barrier is compromised by dryness, cracking, or skin conditions, moisture escapes faster than your body can replace it.
Ointments work by forming a physical, nearly waterproof film over the skin’s surface. This occlusive layer traps moisture underneath, preventing it from evaporating. Research shows that occlusion can increase the water content of the outer skin layer by up to 50%, with measurable hydration improvements in as little as 30 minutes. That’s why ointments are a go-to choice for dry, chapped, or cracked skin and for supporting wound healing.
This same occlusive effect also influences how medications are absorbed. When a drug is formulated in an ointment base, the barrier keeps the active ingredient in close contact with the skin longer, which can improve penetration. Dermatologists have traditionally considered ointment formulations to be more potent than creams containing the same medication, though systematic reviews of topical corticosteroids for psoriasis suggest the real-world difference in effectiveness may be smaller than once thought.
Ointment vs. Cream vs. Gel
The biggest practical difference between these products comes down to their oil-to-water ratio, which affects how they feel, how long they stay on your skin, and which skin types they suit best.
- Ointments are typically 80% oil and 20% water (or less). They feel greasy, stay on the skin for a long time, and provide the strongest moisture barrier. Because they contain so little water, they often don’t need preservatives. Studies on ophthalmic ointments confirm that when water activity is below 0.6, the product simply doesn’t support microbial growth, eliminating the need for added preservatives.
- Creams are roughly a 50/50 mix of oil and water. They spread more easily, absorb faster, and feel lighter on the skin. Because of their higher water content, they require preservatives to prevent bacterial growth.
- Gels are water-based or alcohol-based and contain little to no oil. They absorb quickly and leave no greasy residue, making them popular for the face and areas prone to oiliness. They provide the least occlusion of the three.
For very dry or thick skin, ointments generally outperform creams and gels because they stay put longer and seal in more moisture. For areas that are hairy, oily, or prone to acne, a cream or gel is usually the better choice because ointments can clog pores and feel uncomfortably heavy.
Types of Ointment Bases
Not all ointments are identical. Pharmacists recognize four main categories, each designed for different purposes.
Hydrocarbon (oleaginous) bases are the greasiest option. Made from ingredients like petroleum jelly and paraffin, they’re immiscible with water, meaning they won’t wash off easily. They sit on the skin for extended periods and are the most effective at preventing moisture loss. These are the classic “thick, greasy ointment” most people picture.
Absorption bases can pull in and hold water, forming a water-in-oil mixture. They’re useful when a medication needs to be delivered in a water-containing form but you still want the protective qualities of an oily base. Like hydrocarbon bases, they’re difficult to wash off.
Water-removable bases are technically classified as ointment bases, but they behave much more like creams. They wash off easily with water and feel lighter on the skin.
Water-soluble bases contain no oil at all and are composed of high-molecular-weight ingredients that dissolve in water. They wash off completely, don’t leave a greasy residue, and are sometimes used when the skin needs to stay relatively clean, such as around wounds that require frequent dressing changes.
When Ointments Are the Best Choice
Ointments work best for dry, thick, or scaly skin conditions like eczema, psoriasis plaques, and severely cracked heels or hands. Their staying power makes them ideal for nighttime use, when you can apply a layer before bed without worrying about greasiness on clothes or furniture. Many people apply an ointment to their hands or feet at night and cover them with cotton gloves or socks to maximize absorption.
They’re also commonly used for minor cuts, scrapes, and burns. The occlusive barrier keeps the wound moist, which supports healing and can reduce scarring compared to letting a wound dry out and scab over.
Ointments are less ideal for large, hairy body areas (the chest or scalp, for instance), skin folds like the groin or armpits where trapped moisture can encourage fungal growth, and oily or acne-prone skin where a heavy barrier could worsen breakouts.
How to Apply the Right Amount
Dermatologists use a measurement called the “fingertip unit” to help people gauge how much ointment to use. One fingertip unit is the amount of product squeezed from a standard tube along the length of an adult’s fingertip, from the crease of the first knuckle to the very tip. For an adult male, that’s roughly half a gram; for an adult female, about 0.4 grams. Children need proportionally less, roughly one-third of the adult amount by age four and one-quarter for infants.
As a general guide, one fingertip unit covers an area about the size of two adult palms. So treating one arm from wrist to shoulder takes about three fingertip units, while a full leg requires around six. Applying too little is a common mistake, especially with medicated ointments, because the product needs to form a continuous thin film to work properly. A patchy, uneven layer won’t deliver consistent results.