Do Lip Serums Work, or Are They Irritating Your Lips?

There's no good evidence that lip serums treat dry or chapped lips any better than a plain ointment. Some of them contain the ingredients that make lips worse. A hyaluronic acid serum can make lips look smoother for a while under a balm. Plumpers swell lips with ingredients dermatologists say to keep off dry lips.

Maybe your balm stopped keeping up and a serum looked like the upgrade. Or a plumping gloss promised fuller lips by lunch. Now your lips tingle, peel or look a shade darker at the edges than they did last month.

Do Lip Serums Work Better Than Lip Balm?

For dryness, no. Dryness needs water sealed in, and that's what a balm or ointment does.

Cleveland Clinic says lip skin is thinner and more sensitive than skin elsewhere, and your lips don't contain any oil glands. So they lose water easily. The American Academy of Dermatology (AAD) recommends a thick ointment such as white petroleum jelly for very dry, cracked lips. It says ointment seals in water longer than waxes or oils.

The usual star of a lip serum is hyaluronic acid. Cleveland Clinic says hyaluronic acid is very good at retaining water. It doesn't seal that water in, though. The AAD says ointment seals in water longer than waxes or oils, so if you use a serum, a balm goes on top.

What Does the Research on Lip Serums Show?

Very little, and most of it comes from the companies selling the products. One study gave 36 women aged 22 to 40 a two-step hyaluronic acid lip treatment, at least three times a day for four weeks. The women had mild to moderate lip dryness.

The researchers reported better hydration, texture, color, lines and plumpness. Every woman used the product and knew it, and there was no comparison group. The authors worked for the company behind the product and a research firm.

A trial of a plumping product with capsaicin, cinnamon and menthol finished with 18 adults. All 18 looked fuller 15 minutes after applying it, and 12 of the 18 did at one hour. People reported tingling and heat, which mostly faded within 15 minutes.

Neither study compared the product with plain petroleum jelly. So the fair reading is that a serum may make lips look smoother or fuller for a short time. Nothing shows it heals dry lips better than an ointment.

Which Lip Serum Ingredients Should You Avoid?

Turn the bottle over before you buy, and check it against the AAD's lists for dry, chapped lips.

• Skip: camphor, eucalyptus, fragrance, lanolin, menthol, phenol (or phenyl), propyl gallate, salicylic acid, and the sunscreen filters octinoxate and oxybenzone.
• Skip flavors: the AAD says cinnamon, citrus, mint and peppermint can be especially irritating to dry, chapped lips.
• Look for: white petroleum jelly, petrolatum, mineral oil, dimethicone, ceramides, shea butter, and zinc oxide or titanium dioxide for sun protection.
• Choose: products labeled fragrance-free and hypoallergenic.

Pay most attention to anything sold as tingling, plumping or exfoliating. Cleveland Clinic says to stop a lip product that stings, burns or tingles. The AAD says burning, stinging or tingling means a product is irritating your lips.

A plumper is built to tingle, which puts it at odds with that advice. If your lips are already dry or cracked, that's a reason to leave it on the shelf until they've healed.

Can a Lip Serum Make Your Lips Darker?

It can, through an allergic reaction, and on brown or Black skin that reaction can show up as darker patches. Mayo Clinic lists leathery patches that are darker than usual as a sign of contact dermatitis, typically on brown or Black skin. On white skin, the same reaction more often looks dry, cracked and scaly.

Lip products are a known trigger. A North American study looked at 196 patients referred for patch testing whose only rash was on their lips, and 84% were women. In 38%, the cause was an allergy to something touching their lips. Fragrance and balsam of Peru, a fragrance and flavoring ingredient, were among the most common culprits.

Mayo Clinic says balsam of Peru is also used in toothpastes, mouth rinses and flavorings. It says a contact rash can appear within minutes to hours of exposure and last 2 to 4 weeks.

So if your lips darkened after a new serum, gloss or toothpaste, stop it before buying anything that promises to even out lip color. Serums can't undo a reaction that a product is still causing. Why lips turn dark walks through the other causes, from smoking to sun to medicines.

Do You Need SPF on Your Lips?

Yes, whenever you're outside, and a serum without SPF doesn't count. The AAD advises a non-irritating lip balm with SPF 30 or higher before going outdoors, reapplied every two hours.

Zinc oxide and titanium dioxide are on the AAD's list of ingredients to look for. Octinoxate and oxybenzone are on its list to avoid while your lips are chapped. SPF for lips covers why lips need it and how to keep it on.

Who Might Get Something From a Lip Serum?

If your lips are healthy and you'd like them to look smoother, a fragrance-free hyaluronic acid serum under a balm is reasonable to try. Check the label against the list above first. Add one new lip product at a time, so you know which one is to blame if your lips react.

Skip the serum for now if any of these sound like you:

• Your lips are cracked, peeling or sore. Heal them first with plain petroleum jelly.
• You lick your lips through the day. The AAD says lips get drier as saliva evaporates. Why your lips are always dry covers this and the other habits that keep lips dry.
• A lip product burns or stings, even a little.
• Your lips have darkened since you started a new product.

If you use strong actives on your face too, this guide to dark skin and actives covers the extra care brown and Black skin needs.

When to See a Doctor About Your Lips

The AAD says self-care usually heals dry, chapped lips in 2 to 3 weeks. If yours haven't improved by then, see a board-certified dermatologist. The AAD also names allergic reactions, yeast infections and actinic cheilitis, a precancerous condition that makes lips dry and scaly, as other causes.

Mayo Clinic advises seeing a doctor if a contact rash doesn't get better within three weeks, or if it affects your mouth or face. The study above found patch testing useful for tracking down lip allergies, so ask about it. Get care quickly if you have a fever or pus oozing from blisters, which can point to infection.

Mayo Clinic says to seek emergency care if your tongue, lips, mouth or throat start swelling or you have trouble breathing. Call 911 or your local emergency number.

Frequently Asked Questions

Is Hyaluronic Acid Good for Dry Lips?

It holds water, so it can help lips look smoother. It doesn't seal that water in, so use a balm or petroleum jelly over it. For cracked lips, the ointment alone is the better choice.

Why Does My Lip Plumper Burn?

The plumper tested in one trial used capsaicin, cinnamon and menthol, and people felt heat and tingling as their lips swelled. The AAD says to stop any lip product that burns or stings.

Can a Lip Serum Replace Lip Balm?

Not for dry lips. A serum adds water or active ingredients, while a balm or ointment seals moisture in. If you use both, the serum goes on first and the balm on top.