# 7 Ingredient Frenemies, According to Dermatologists

To avoid skin irritation and other side effects, avoid the following skincare ingredient combinations. Dermatologists warn against the following ingredient frenemies.

As your skincare routine becomes more advanced, you’ll naturally begin incorporating more [active ingredients](/content/articles/skincare-active-ingredients/index.html). However, there are certain active ingredients that don’t play well together (aka ingredient frenemies). When used separately, they can work wonders. When used together in the same routine, not so much.

This isn’t to say you can’t use some of these active ingredients at all — just be sure to use them at different times of the day or even on different days altogether to minimize irritation.

To ensure you’re getting the most out of your skincare routine, here are the active ingredient combinations to avoid. Like all things, there are some exceptions. If you’re new to skincare or have sensitive skin, try avoiding these ingredient frenemies wherever possible. And don’t just take our word for it, these recommendations come from professionals.

## Retinol and Vitamin C

[Retinol](/content/ingredients/retinol/index.html) alone is associated with skin irritation, so it’s no surprise that it doesn’t play well with others. This is a derivative of vitamin A, so it has antioxidant and anti-aging properties. However, we recommend approaching retinol products with caution since retinol is known for causing redness, scaling, itching, and dryness, according to the [American Osteopathic College of Dermatology](https://www.aocd.org/page/Retinoidstopical).

[Ross Perry, M.B.B.S.](https://www.cosmedics.co.uk/doctors-surgeons/dr-ross-perry/), a skin doctor and the Medical Director of Cosmedics Skin Clinics, doesn’t recommend using retinol alongside most active ingredients, especially [vitamin C](/content/ingredients/vitamin_c/index.html).

“Avoid using Retinol and vitamin C together as it will only cause irritation because both products are what’s known as active ingredients,” explains Perry. If you choose to use retinol, he says “it’s best to use retinol at night when the skin repairs itself and vitamin C during the day.”

For those who want to avoid retinol altogether to reduce irritation further, a more gentle alternative is [psoralea corylifolia (bakuchiol)](/content/ingredients/psoralea_corylifolia_bakuchiol/index.html), an up-and-coming clean skincare ingredient known for having similar anti-aging properties as retinol without the harshness.

_Ross Perry, M.B.B.S._

## Probiotics and Antibiotics

You may have heard of the benefits of probiotics for your gut health, but they’re also beneficial for skin health. Like the gut, the skin has its own microbiome full of healthy bacteria. One way to support that healthy bacteria is with probiotics, which can be taken orally or applied topically to the skin with [probiotic skincare](/content/articles/probiotic-skincare/index.html).

However, probiotic skincare shouldn’t be used at the same time as antibiotic creams, according to [Tanya Kormeili, MD, FAAD](http://www.drkormeilidermatology.com/'). "As we learn more about the perfect balance between the good and bad bacteria on our skin, it is important to know that we should not combine products with probiotics and apply them at the same time as any antibiotics,” says Kormeili. “Often your dermatologist will give you a topical antibiotic cream to help control acne or rosacea. This will fight the bad organisms on your skin. You can replenish the good ones with the good probiotics but it is best to use them at a different time so as not to kill the effects of the probiotic with the antibiotic topical application."

_Tanya Kormeili, MD, FAAD_

Using probiotics and antibiotics at the same time will only counteract each other. Kormeili recommends following up on your antibiotic treatment with probiotics but only once you’re done with the antibiotics.”

## Glycolic Acid and Retinol

[Glycolic acid](/content/ingredients/glycolic_acid/index.html) is an active ingredient in many chemical exfoliants to remove layers of dead skin cells. While glycolic acid is a beneficial active ingredient to have in your arsenal, it’s not one you should combine with retinol, which is infamous for causing irritation on its own or when paired with other ingredients.

Perry explains why: “Retinol and [alpha hydroxy acids (AHAs)](/content/articles/AHA_BHA/index.html) like glycolic acid should not be used together. Both are effective products for anti-aging and help to speed skin cell turnover. Because they both exfoliate the outer skin of the skin, using both products at the same time can cause irritation and sensitivity.”

## Vitamin C and Benzoyl Peroxide

“Vitamin C and benzoyl peroxide should not be used together,’ says [Ophelia Veraitch, PhD, MRCP](https://drophelia.com/pages/about), a dermatologist in London. “Vitamin C is an antioxidant whereas benzoyl peroxide is the opposite — an oxidant used to kill bacteria. So there is no point using these two skincare ingredients together.”

_Ophelia Veraitch, PhD, MRCP_

If you rely on your benzoyl peroxide face wash or spot treatment to [prevent acne](/content/articles/how-to-prevent-acne/index.html), try using these products at a different time or on a different day than your vitamin C products.

## Salicylic Acid and Glycolic Acid

Like AHAs, beta hydroxy acids (BHAs) are also used as chemical exfoliants. They’re especially beneficial for [acne-prone skin](/content/articles/adult_acne_causes/index.html). An example of BHAs is [salicylic acid](/content/ingredients/salicylic_acid/index.html), which is commonly found in cleansers, toners, and exfoliants formulated to unclog the pores and reduce inflammation.

“Avoid using glycolic acid and salicylic acid at the same time,” instructs Perry. “It’s correct to say that both help to rid the skin of dead skin cells, but using both at the same time can increase sensitivity in the skin in the form of redness, dryness, flakiness, and itchiness.”

One solution is to use your [salicylic acid cleansers](/content/reviews/5_best_salicylic_acid_cleansers_for_acne-prone_skin/index.html) in the morning, but save your [chemical exfoliants](/content/reviews/best-non-toxic-chemical-exfoliators/index.html) for the evening. If using other active ingredients at night, you can alternate days.

## Benzoyl Peroxide and Retinol

“Retinol and [benzoyl peroxide](/content/ingredients/benzoyl_peroxide/index.html) are both great acne-fighting products. However, they shouldn’t be used together,” according to Perry. “Benzoyl peroxide may deactivate the retinoid molecule, making the product essentially useless on the skin. It’s best to use benzoyl peroxide in the morning and retinol in the evening.”

It’s especially important to avoid using benzoyl peroxide and other peeling agents with tretinoin, a prescription-strength form of retinol, according to the [Mayo Clinic](https://www.mayoclinic.org/drugs-supplements/tretinoin-topical-route/precautions/drg-20066521). Tretinoin is only available through your doctor or dermatologist but requires extra care.

You’re likely to find benzoyl peroxide in many [facial washes](/content/articles/best-cleanser-and-exfoliator-for-skin-type/index.html) and spot treatments geared towards acne. Stick to these products in the morning if you use retinol at night. If you’re trying to decide between the two, benzoyl peroxide is more gentle.

## Niacinamide and Vitamin C

[Niacinamide](/content/ingredients/niacinamide/index.html) is vitamin B3, an antioxidant commonly found in skincare serums. It’s a popular ingredient since the [benefits of niacinamide](/content/articles/niacinamide/index.html) include potent antioxidant properties, reduced inflammation, smaller pore size, and fewer breakouts. If you plan on incorporating a [niacinamide serum](/content/reviews/_5_best_clean_niacinamide_serums/index.html) into your routine, you may want to reconsider pairing it with vitamin C if you have sensitive skin.

According to Dr. Perry, “Niacinamide and vitamin C are great products to help with acne-prone and uneven skin. However, using them together can cause sensitivity and further breakouts.”

There are some exceptions to these rules of ingredient frenemies, and vitamin C and niacinamide are an example. For some people who don’t have sensitive skin, pairing the two antioxidants has no side effects. This one depends on your skin types and whether your products work harmoniously together.

When in doubt, Dr. Perry recommends using vitamin C on its own.

### Combining Skincare Active Ingredients Safely

Safety first in all things, including your skincare routine. Avoiding skincare frenemies may seem daunting if you want to reap the benefits of these active ingredients. Assuming the ingredients you've chosen are clean and gentle, there is a way around this.

[Viseslav Tonkovic-Capin](https://dermboard.org/about-the-dermboard/), a dermatologist in the greater Kansas City metro area, says you can use active ingredients concurrently as long as you wait two hours between applications. If you don’t have the patience, simply use one ingredient in the morning and another at night. You can also use them on alternating days.

_Dr. Viseslav Tonkovic-Capin_

#### Sources

[American Osteopathic College of Dermatology: “Retinoids, topical”](https://www.aocd.org/page/Retinoidstopical) [Mayo Clinic: “Tretinoin (Topical Route”](https://www.mayoclinic.org/drugs-supplements/tretinoin-topical-route/precautions/drg-20066521)