A clay mask is the default advice for blackheads, and it is easy to see why: clay is an old, familiar oil absorber, and a blackhead is oil and dead skin sitting in a pore. So does a clay mask for blackheads actually work, or does it just feel like it should?
Here is the short version before the detail. One 4-week study found fewer blackheads and less oil with a kaolin-and-bentonite mask, but it had no comparison group, it was funded by the mask's maker, and it found no change in pore size. Dermatologists recommend a retinoid for blackheads. Clay is a maintenance step, not a fix.
• In one 4-week study of a kaolin-and-bentonite mask, a dermatologist counted 65.77% fewer open comedones (blackheads) by week 4, but there was no comparison group and the maker funded it.
• The same study found no significant change in pore area, so a clay mask is best judged as an oil-control step, not a way to shrink pores.
• The American Academy of Dermatology says dermatologists recommend a retinoid for blackheads, and that an over-the-counter adapalene product can unclog pores without a prescription.
• We found no published trial of multani mitti or rhassoul on blackheads, so treat them as a weekly oil-absorbing mask and keep expectations modest.
What Is a Blackhead, and Why Is It Black?
A blackhead is an open pore plugged with excess oil and dead skin cells, and it is dark because of a chemical reaction, not dirt. The American Academy of Dermatology (AAD) explains that as the buildup widens the pore opening, it reacts with oxygen in the air, much like a cut apple turning brown. The medical name is an open comedo.
The AAD also advises against squeezing blackheads, because it can cause an infection or a permanent scar. A mask works on the skin's surface, so the honest question is how much it can do for a plug that sits inside the pore.
Does a Clay Mask Actually Reduce Blackheads?
It may help, but the best evidence we found is small and comes with real limits. In a 2023 study in Skin Research and Technology, 60 adults with oily or combination skin completed a 4-week trial of a commercial clay mask (kaolin and bentonite, plus other ingredients including thermal spring water and vitamin B5) used twice a week. A blinded dermatologist counted lesions. By week 4, open comedones, the technical name for blackheads, were down 65.77%, closed comedones were down 46.44%, and skin oiliness readings were down 29.90%.
Why would clay do anything at all? Clay minerals are widely used in cosmetics as adsorbents or absorbents, according to a 2017 review in the International Journal of Pharmaceutics. The usual explanation for an oil-control mask is that clay binds surface oil and debris and rinsing carries both away, though the study above measured outcomes, not that mechanism.
Now the limits, because they matter as much as the numbers.
No comparison group. The paper describes a single group using the mask, so it cannot show how much of the change came from the mask itself.
Funded by the manufacturer. The study was funded by L'Oréal, which owns the mask's brand, La Roche-Posay, and all of its authors list L'Oréal as their affiliation.
A finished product, not plain clay. The mask contained added ingredients, so its results cannot be assumed to carry over to a raw clay powder.
Small numbers. Only 40 of the 60 people who finished had dermatologist lesion counts.
Can a Clay Mask Shrink Pores or Replace a Retinoid?
We found no evidence that it does either. In the same study, pore area showed no significant change over the 4 weeks, so a clay mask should not be sold, or bought, as a pore shrinker. It reduced oil and blackhead counts, which is a different outcome.
On treatment, the AAD says that if you have blackheads you want a product that can unclog pores, and that an acne medication containing adapalene can unclog pores and stop new blackheads forming, with no prescription required. We found no trial that compares a clay mask with adapalene, so we cannot say how the two stack up. If blackheads are your main concern, ask a pharmacist or dermatologist about adapalene, and consider a clay mask an optional extra for oil control.
Which Clay Should You Use for Blackheads?
For oily or combination skin, multani mitti is the stronger absorber, and for sensitive or drier skin that still gets congested, rhassoul is the gentler pick. Neither has been tested on blackheads in a published trial that we could find, so this is a matching-clay-to-skin question, not a proven result.
Sampson's Multani Mitti Clay is a single-ingredient fuller's earth sold as a raw powder, and it sits at the strong-absorber end of the clay range. Our product page lists congestion and blackheads among who it is for, alongside oily and combination skin. That is a traditional-use claim, not a tested result. Our Rhassoul Clay is a Moroccan clay and a medium absorber that swells with water, which suits skin that congests but cannot take a stronger mask.
Sampson Multani Mitti Clay
Multani Mitti Clay
Single-ingredient fuller's earth, milled ultra-fine and sold as a raw powder. No water, fragrance or preservative. The stronger absorber, for oily and combination skin.
Shop now → ✓ 30-day money-back guarantee · Free shipping over $75
Sampson Rhassoul Clay
Rhassoul Clay
Single-ingredient Moroccan rhassoul from the Atlas Mountains, a fine silky powder with nothing added. A medium absorber that swells with water, for sensitive skin that still congests.
Shop now → ✓ 30-day money-back guarantee · Free shipping over $75Neither one is the finished mask used in the study, so its numbers cannot be assumed to carry over to them. For a side-by-side, read rhassoul clay vs multani mitti, and for the basics on the clay itself, start with What Is Multani Mitti? If you would rather use a soap than a mask, see our guide to African black soap for blackheads.
How Do You Use a Clay Mask on Blackheads?
Mix the powder into a smooth paste, spread a thin layer over the congested areas, rinse while it is still slightly tacky, and repeat once or twice a week, not daily. If your skin is reactive, patch-test a small amount on your inner forearm first.
- Mix. Combine about 1 teaspoon of multani mitti with enough water or rosewater to make a spreadable paste. For rhassoul, add water a little at a time until it forms a smooth paste. Use a non-metal bowl and spoon.
- Apply. Spread a thin, even layer over clean skin where blackheads collect, such as the nose, chin and forehead. Keep it away from the eye area.
- Wait. Leave multani mitti on until it is dry to the touch but still slightly tacky, and rhassoul for 10 to 15 minutes. Participants in the study were told to leave the mask on for 5 to 10 minutes.
- Rinse. Rinse with lukewarm water and pat dry. Follow with a light moisturizer if your skin feels tight.
- Repeat. Use it once or twice a week. The study used a mask twice a week, and more often than that is more than oily skin needs.
Do not let the mask dry to a hard crack, and do not squeeze blackheads afterward. If your skin stings, burns or turns red, rinse the mask off and stop using it.
When Should You See a Dermatologist About Blackheads?
See a dermatologist if blackheads keep coming back, if you also get deep, painful breakouts, or if your skin is irritated or scarring. The AAD says deep, painful acne needs a treatment that works on clogged pores, bacteria, inflammation and excess oil, and that takes a dermatologist's help. A clay mask is not a substitute for that care.
Frequently Asked Questions
Does a clay mask remove blackheads?
It may reduce them. In one 4-week study of a kaolin-and-bentonite mask, a dermatologist counted 65.77% fewer open comedones by week 4. The study had no comparison group and was funded by the maker, so it is encouraging, not conclusive.
How often should you use a clay mask for blackheads?
Once or twice a week. The study used a mask twice a week, and our clay pages suggest one to two times a week, not daily, because strong absorption can leave skin tight.
Will a clay mask shrink pores?
There is no evidence that it does. In the same study, pore area showed no significant change over 4 weeks of twice-weekly use.
Is multani mitti or rhassoul clay better for blackheads?
Neither has been tested on blackheads in a published trial we could find. Multani mitti is the stronger absorber and suits oily or combination skin, while rhassoul is gentler and suits sensitive or drier skin that still congests.