A suspension in skincare is a product where active ingredients exist as solid particles dispersed throughout a liquid or cream base, rather than being fully dissolved into it. If you’ve ever picked up a product from The Ordinary with “Suspension” in the name, or noticed a sunscreen that separates in the bottle, you’ve encountered this formulation type. Understanding what makes a suspension different from other product types helps you use it correctly and get the most from the active ingredients inside.
How a Suspension Differs From Other Formulations
Skincare products generally fall into three categories based on how their ingredients are mixed: solutions, emulsions, and suspensions. In a solution, ingredients are completely dissolved, the way sugar dissolves in water. You get a clear, uniform liquid where everything is evenly distributed at a molecular level. In an emulsion, two liquids that don’t naturally mix (like oil and water) are blended together using an emulsifier to keep them stable. Most moisturizers and lotions are emulsions.
A suspension is different from both. It contains solid particles that are too large to dissolve into the surrounding liquid. These particles are visible to the naked eye in many cases, and because they aren’t dissolved, they naturally settle over time. This is the key trait of a suspension: it’s inherently unstable and will separate if left sitting. That’s not a defect. It’s just physics.
The reason brands choose a suspension format is usually about concentration. Some active ingredients, like zinc oxide, azelaic acid, or certain vitamins, can be delivered at higher percentages when they don’t need to be dissolved. Dissolving an ingredient requires the right solvent and has natural limits. Suspending it as fine particles bypasses that constraint, allowing the product to carry more of the active than a solution could.
Common Active Ingredients in Suspensions
The most well-known suspension products in mainstream skincare contain azelaic acid, typically at 10% concentration for over-the-counter formulas. Azelaic acid targets uneven skin tone, texture, and breakouts, and it doesn’t dissolve easily into a lightweight serum base. Suspending it allows the product to deliver a meaningful dose in a format you can spread across your skin.
Mineral sunscreens are another major category. Zinc oxide and titanium dioxide, the active filters in physical sunscreens, are mineral particles that sit on the skin’s surface rather than absorbing into it. These ingredients are suspended in their base formula, which is why many mineral and “milk” sunscreens have a ball bearing inside the bottle to help you remix the product before application. Vitamin C in its pure powder form (ascorbic acid) also appears in suspension products, since it’s notoriously difficult to keep stable in solution.
Why Suspensions Feel Different on Your Skin
If you’ve used a suspension product and noticed a slightly gritty, thick, or chalky texture, that’s the undissolved particles you’re feeling. This is normal and expected. Unlike serums that glide on as a smooth liquid, suspensions often feel heavier and may leave a matte or slightly textured finish. The particles haven’t been broken down small enough to feel invisible, so your fingertips pick up on them as you apply.
Suspensions are also more prone to pilling, that annoying effect where tiny rolls of product form on your skin as you layer other products over them. Research published in 2024 found that ingredients like zinc oxide and titanium dioxide, both common in suspension-format sunscreens, can be incompatible with water-based products layered on top. The study also found that pilling is more likely on drier skin with lower oil levels, so your skin type plays a role too. If you notice pilling with a suspension product, adjusting your application method or the products you layer over it usually helps more than switching the suspension itself.
How to Use a Suspension Product
The single most important step is shaking or mixing the product before each use. Because suspensions separate naturally, the active ingredient sinks to the bottom over time. If you squeeze or pump the product without mixing it first, you might get a dose that’s mostly base with very little active, or a concentrated glob of undissolved ingredient. Sunscreen users learn this lesson quickly: skipping the shake can mean a burst of separated oil instead of a uniform product. Some bottles include a small mixing ball inside to help with redistribution.
When layering, suspensions generally work best applied to clean skin before heavier creams and oils. Because the solid particles need direct contact with your skin to work, burying them under layers of serum can reduce their effectiveness and increase pilling. A thin, even layer pressed gently into the skin (rather than rubbed aggressively) gives the particles the best chance to distribute evenly. Let the suspension set for a minute or two before applying your next product.
If a suspension feels too gritty or thick on its own, you can mix a small amount into your moisturizer in your palm before applying. This dilutes the concentration slightly but can make the texture more comfortable, especially for products like azelaic acid suspensions where the grittiness bothers some users.
Suspension vs. Cream Versions of the Same Ingredient
You’ll sometimes see the same active ingredient available as both a suspension and a cream or serum. Azelaic acid is a good example: it comes in suspension form at 10% over the counter, but also in smoother cream formulations. The difference is usually about how the ingredient is processed and what trade-offs the brand made. A cream version dissolves or micronizes the active into a smoother base, which feels more elegant but may use a lower concentration or require additional stabilizers. A suspension skips that step, delivering the raw active at a higher load in exchange for a less refined texture.
Neither format is inherently better. If you want the highest concentration of an active and don’t mind a grittier feel, a suspension delivers. If texture and layering ease matter more to you, a cream or serum version of the same ingredient may fit your routine better, even if the percentage is slightly lower. The active ingredient itself works the same way regardless of the delivery vehicle.