Ingredient conflict and pore-clogging checker

How to use the checker

There are two ways to check. Pick your actives is the fast option: tick the ingredients you use, such as benzoyl peroxide, adapalene and vitamin C, and you get a verdict for every pair, with the reasoning and sources. Paste ingredient lists checks a real routine. Paste the full ingredient list from up to four products, say whether you use each one in the morning, evening or both, and the checker compares only the products that actually meet on your skin. Prefer to read? Our ingredient pairing guides explain the most-asked combinations one by one.

For over-the-counter acne products, the active ingredient and its strength are in the “Drug Facts” box (for example, “Benzoyl peroxide 5%”). Include that line: the checker notes when a strength is outside the range the FDA allows for over-the-counter acne products. For cosmetics, copy the “Ingredients” list from the box or the retailer’s listing.

What the verdicts mean

• Avoid combining: A label or strong evidence says not to use these together, or combining them brings no benefit and more irritation.
• Use at different times: Both can be part of your routine, but apply them at different times of day (or on different nights).
• OK with caution: No harmful chemical reaction is known, but irritation adds up. Introduce slowly and watch your skin.
• Generally fine together: No known problem combining these.

Why some acne ingredients clash

Almost every flag in the checker comes down to one of three things.

1. One ingredient breaks the other down

Benzoyl peroxide is a strong oxidizer. In a 1998 lab study it degraded about half of a standard tretinoin gel within roughly two hours under light, while adapalene stayed stable. That is why we suggest separating tretinoin and benzoyl peroxide but rate adapalene with benzoyl peroxide as fine. The same chemistry is behind our advice to keep vitamin C and benzoyl peroxide apart.

2. Irritation adds up

Most “conflicts” are not chemical at all. Retinoids, exfoliating acids and benzoyl peroxide each dry and irritate the skin, and together they can leave it raw. The FDA requires over-the-counter acne drugs to warn that irritation and dryness are more likely if you use another topical acne medication at the same time. Drug labels go further for some pairs: the Differin (adapalene) prescribing information says to avoid alpha hydroxy and glycolic acid products, and the tretinoin label advises particular caution with salicylic acid, sulfur and resorcinol. See adapalene with glycolic acid and tretinoin with salicylic acid.

3. Cosmetic side effects

Some pairs are harmless but unwelcome together. The label for dapsone gel (Aczone) warns that using it with benzoyl peroxide can temporarily turn skin and facial hair yellow or orange. Read more about using dapsone with benzoyl peroxide.

And some famous “conflicts” don’t hold up. The warning against using niacinamide with vitamin C comes from a 1963 lab study of the two in solution, not from any evidence of harm on skin.

How much to trust “pore-clogging” (comedogenic) flags

The idea that cosmetics can cause acne was popularized in 1972, when dermatologists Albert Kligman and Otto Mills described “acne cosmetica”. Much of the testing that followed used the rabbit ear, which forms plugged follicles when irritating or comedogenic substances are applied. James Fulton’s rabbit-ear studies in the 1980s produced the 0-to-5 ratings that still circulate online, and named isopropyl myristate and acetylated lanolin alcohol as major offenders.

The trouble is that the model was questioned almost from the start. A 1982 review in the Journal of the American Academy of Dermatology pointed to problems with the test method and a lack of correlation with human experience. A 2006 re-evaluation argued that finished products should be tested on people rather than judged ingredient by ingredient. Raw ingredients were often tested undiluted, and the rest of a formula can change how an ingredient behaves.

So the checker shows three levels, each with its own explanation:

• Flagged in rabbit-ear studies: we could identify a study that found it comedogenic in rabbits.
• On older comedogenicity lists: it appears on widely shared lists derived from rabbit-ear testing, but we have not verified its individual score against the original paper.
• Mixed or low ratings: older lists disagree or rate it low; shown only in the database below, not as a flag.

If a product with a flagged ingredient works for you, there’s no need to stop using it. If you are breaking out and suspect a product, the more useful test is to stop that product for several weeks and see what happens.

What this checker can’t tell you

• Concentrations. Ingredient lists are in descending order but rarely show percentages, so we can’t tell a 10% glycolic acid peel from a trace amount.
• Formulation tricks. Encapsulated or specially stabilized ingredients, such as microencapsulated tretinoin with benzoyl peroxide, can behave differently from the general rule. Follow the product’s own directions.
• Your skin. Allergies, eczema, rosacea and general sensitivity change what you can tolerate.
• Anything outside our rules. If a pair isn’t covered, the checker says so rather than guessing.

Key ingredient combinations at a glance

Every rule the checker uses, without needing JavaScript. Rows with a link have a full guide.

Key ingredient combinations at a glance: verdict, reason and guide for each combination

Combination	Verdict	Why
Adapalene + AHAs (glycolic, lactic, mandelic acid)	Avoid combining	Differin prescribing information says to avoid AHA and glycolic acid products. Skip AHA toners, peels and serums while using adapalene, or ask a dermatologist about a plan.
Retinoids (any) + another retinoids (any)	Avoid combining	Don't double up on retinoids. Pick one retinoid and use it consistently.
Benzoyl peroxide + Dapsone	Use at different times	Dapsone and benzoyl peroxide can stain skin orange. Use them at different times of day (for example, benzoyl peroxide wash in the morning, dapsone at night).
Benzoyl peroxide + Cosmetic retinoids (retinol, retinal, retinyl esters)	Use at different times	Keep benzoyl peroxide and retinol apart. Use benzoyl peroxide in the morning or as a short-contact wash, and retinol at night.
Benzoyl peroxide + Tretinoin	Use at different times	Benzoyl peroxide can break down standard tretinoin. Use benzoyl peroxide in the morning (or as a wash) and tretinoin at night, unless your prescriber says otherwise.
Benzoyl peroxide + Vitamin C (L-ascorbic acid)	Use at different times	Benzoyl peroxide may oxidize vitamin C. Vitamin C in the morning, benzoyl peroxide at night (or as a rinse-off wash).
Retinoids (any) + Vitamin C (L-ascorbic acid)	Use at different times	Vitamin C in the morning, retinoid at night. Apply vitamin C in the morning under sunscreen.
Adapalene + BHA (salicylic acid and relatives)	OK with caution	Adapalene plus salicylic acid can be too irritating together. Use salicylic acid as a wash in the morning and adapalene at night, or alternate nights.
Benzoyl peroxide + Other prescription retinoids (tazarotene, trifarotene)	OK with caution	Ask your prescriber how to combine these. Follow your prescriber's timing instructions.
Tretinoin + BHA (salicylic acid and relatives)	OK with caution	Tretinoin's label advises caution with salicylic acid. Don't apply both at the same time when starting out; alternate nights or use salicylic acid only as a wash.
Tretinoin + Sulfur and resorcinol	OK with caution	Tretinoin's label advises caution with sulfur and resorcinol. Use them at different times, or pick one.
AHAs (glycolic, lactic, mandelic acid) + BHA (salicylic acid and relatives)	OK with caution	Stacking AHAs and BHAs raises the irritation risk. Use one product that contains both, or alternate days.
Benzoyl peroxide + AHAs (glycolic, lactic, mandelic acid)	OK with caution	Benzoyl peroxide and AHAs: watch for irritation. Use them at different times of day.
Benzoyl peroxide + Azelaic acid	OK with caution	Two acne treatments, more irritation. Start one at a time.
Benzoyl peroxide + BHA (salicylic acid and relatives)	OK with caution	Benzoyl peroxide and salicylic acid: effective, but drying. Use one as a wash and the other as a leave-on, or split them morning and night.
Benzoyl peroxide + Sulfur and resorcinol	OK with caution	Two OTC acne drugs, more dryness. If irritation occurs, use only one at a time.
Retinoids (any) + AHAs (glycolic, lactic, mandelic acid)	OK with caution	Retinoids and AHAs are usually better on different nights. Use them on alternate nights rather than layered.
Retinoids (any) + BHA (salicylic acid and relatives)	OK with caution	Retinoids and salicylic acid add up the irritation. Start with one, then add the other on alternate nights once your skin is used to it.
Retinoids (any) + Sulfur and resorcinol	OK with caution	Two acne treatments, more dryness. Use at different times of day, or pick one.
AHAs (glycolic, lactic, mandelic acid) + Vitamin C (L-ascorbic acid)	OK with caution	Low-pH layers can sting. Try vitamin C in the morning and acids at night.
Azelaic acid + AHAs (glycolic, lactic, mandelic acid)	OK with caution	Azelaic acid plus AHAs can sting. Alternate them, or keep one to a rinse-off product.
Azelaic acid + BHA (salicylic acid and relatives)	OK with caution	Azelaic acid plus salicylic acid can sting. Alternate them, or use salicylic acid only as a wash.
BHA (salicylic acid and relatives) + Sulfur and resorcinol	OK with caution	Two OTC acne drugs, more dryness. If irritation occurs, use only one at a time.
BHA (salicylic acid and relatives) + Vitamin C (L-ascorbic acid)	OK with caution	Low-pH layers can sting. Try vitamin C in the morning and salicylic acid at night or as a wash.
Benzoyl peroxide + Drying or astringent ingredients (denatured alcohol, witch hazel)	OK with caution	Drying products add to benzoyl peroxide irritation. Choose a gentle, non-drying cleanser and moisturizer.
PHAs (gluconolactone, lactobionic acid) + BHA (salicylic acid and relatives)	OK with caution	Multiple exfoliating acids add up. Use one exfoliating acid product at a time.
PHAs (gluconolactone, lactobionic acid) + AHAs (glycolic, lactic, mandelic acid)	OK with caution	Multiple exfoliating acids add up. Use one exfoliating acid product at a time.
Retinoids (any) + Drying or astringent ingredients (denatured alcohol, witch hazel)	OK with caution	Drying products can make retinoid irritation worse. Use a gentle, non-medicated cleanser and skip astringent toners.
Retinoids (any) + PHAs (gluconolactone, lactobionic acid)	OK with caution	PHAs are gentler, but still an extra exfoliant. Try alternating nights first.
Benzoyl peroxide + Adapalene	Generally fine together	Adapalene and benzoyl peroxide are a recognized combination. Start slowly (every other night) if your skin is sensitive, then build up.
Benzoyl peroxide + Topical antibiotics (clindamycin, erythromycin, minocycline)	Generally fine together	Benzoyl peroxide is recommended alongside topical antibiotics. Use as your prescriber directs; many products combine both in one gel.
Niacinamide + Vitamin C (L-ascorbic acid)	Generally fine together	Niacinamide and vitamin C can be used together. Use them in the same routine, or split them morning and evening if the combination stings.
Azelaic acid + Niacinamide	Generally fine together	Azelaic acid and niacinamide are generally fine together. Apply azelaic acid first, then niacinamide, or use a product with both.
Niacinamide + BHA (salicylic acid and relatives)	Generally fine together	Niacinamide and salicylic acid are generally fine together. Apply salicylic acid first, then niacinamide.
Retinoids (any) + Topical antibiotics (clindamycin, erythromycin, minocycline)	Generally fine together	Retinoid plus topical antibiotic is a guideline combination. Follow your prescriber's directions.
Retinoids (any) + Azelaic acid	Generally fine together	Retinoids and azelaic acid can be combined. Introduce one at a time.
Retinoids (any) + Niacinamide	Generally fine together	Retinoids and niacinamide are generally fine together. Apply the retinoid first, then a niacinamide serum or moisturizer.
Benzoyl peroxide + Niacinamide	Generally fine together	Benzoyl peroxide and niacinamide are generally fine. Use a niacinamide moisturizer after your benzoyl peroxide if you like.
Niacinamide + AHAs (glycolic, lactic, mandelic acid)	Generally fine together	Niacinamide and AHAs are generally fine together. Apply the acid first, then niacinamide. Use sunscreen daily with AHAs.
Retinoids (any) + Humectants (hyaluronic acid, glycerin)	Generally fine together	Hydrating ingredients pair well with retinoids. Apply the retinoid, then a moisturizer or hydrating serum.

Verdicts: Avoid combining means a label or strong evidence says not to, or there is no benefit and more irritation. Use at different times means morning versus evening, or alternate nights. OK with caution means no harmful reaction is known but irritation adds up. Linked rows have a full guide. Rules last checked 2026-09-23.

“Can I use X with Y?” guides

Detailed answers for the most-asked combinations, each with how-to-layer steps and sources. See all of them on the ingredient pairing guides index.

Avoid combining

• Can You Use Retinol With Tretinoin? No need. Pick one retinoid
• Can You Use Adapalene With Glycolic Acid? Differin prescribing information says to avoid it

Use at different times

• Can You Use Tretinoin With Benzoyl Peroxide? Yes, but usually not at the same time
• Can You Use Retinol With Benzoyl Peroxide? Yes, but keep them to different times of day
• Can You Use Vitamin C With Benzoyl Peroxide? Yes, but at different times of day
• Can You Use Retinol With Vitamin C? Yes. Vitamin C in the morning, retinol at night
• Can You Use Dapsone (Aczone) With Benzoyl Peroxide? Yes, but at different times of day

OK with caution

• Can You Use Retinol With Salicylic Acid? Yes, with care. Irritation adds up
• Can You Use AHA and BHA Together? Yes, but do not layer separate products every day
• Can You Use Benzoyl Peroxide and Salicylic Acid Together? Yes, but they are drying together
• Can You Use Retinol With Glycolic Acid? Yes, but alternate nights instead of layering
• Can You Use Tretinoin With Salicylic Acid? Only with care, and ideally with your prescriber’s OK
• Can You Use Adapalene With Salicylic Acid? Yes, with care. Start with one at a time

Generally fine together

• Can You Use Adapalene With Benzoyl Peroxide? Yes. It is a well-established pairing
• Can You Use Niacinamide With Vitamin C? Yes. The old warning does not hold up for skin care
• Can You Use Azelaic Acid With Niacinamide? Yes. They are generally fine together
• Can You Use Retinol With Niacinamide? Yes. A low-risk pairing
• Can You Use Clindamycin With Benzoyl Peroxide? Yes. They are recommended together
• Can You Use Azelaic Acid With Retinol? Yes. Introduce them one at a time
• Can You Use Niacinamide With Salicylic Acid? Yes. They are generally fine together
• Can You Use Retinol With Hyaluronic Acid? Yes. Hydration is a good partner for retinoids

Browse the ingredient database

The checker recognizes 146 ingredients and their common INCI names. Our acne ingredient database lists every one, grouped by type, with what it does, its FDA status, any pore-clogging note and its sources.