Salicylic Acid (BHA): Literally Everything You Need to Know
Salicylic Acid (BHA), a.k.a the ingredient in all those acne washes that doesn’t work. Frustrating huh? Don’t blame the poor guy though. It’s not his fault.
He’s actually pretty awesome, only companies don’t formulate him properly so people think he sucks. But, that’s why we’re here — to make his life a little easier and boost up his coolness factor.
We’ll be discussing what salicylic acid is, its benefits, side effects, how to use it, and what products are properly formulated. Without further ado…
Table of Contents
What is Salicylic Acid?
Salicylic Acid, often referred to as BHA (beta hydroxy acid), is a naturally occurring hormone produced by plants as a defense mechanism against environmental or pathogenic stress. (1) It can be synthesized from Willow trees and brush, thus the term “willowbark extract” you might have seen in some cosmetic formulas.
Dietary sources of Salicylic Acid (SA) are commonly found in fruits, vegetable, herbs, spices, tea, wine, fruit juice, and ketchup. It’s nutritional content may also play a role in lowering the risk of butthole cancer. (2, 3)
I mean… colon cancer. Apologies.
As far as skincare products go, Salicylic Acid (SA) is pH dependent requiring an acidity level of 4 or lower to effectively exfoliate and treat acne at its maximum capacity. Anything higher reduces its potency, and a pH above 7 essentially renders it useless. (4) Which may be the reason you found that drugstore spot treatment as effective as your mom’s advice.
“Just wash your face, honey.”
Benefits:
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Salicylic Acid Treats Acne.
Unlike most AHAs, SA is oil soluble allowing it to penetrate into pores and dissolve clogs. It also exfoliates superficially through desquamation of the stratum corneum. (5)
English translation = it removes dead skin cells from the outer most layer of skin.
It’s anti-inflammatory, anti-bacterial, a keratolytic, and prevents clogged pores meaning it addresses all major causes of acne. (6)
Multiple clinical trails have shown that using 0.5% to 2.0% Salicylic Acid pads (like Stridex in a red box) reduces the severity of acne, with some studies showing it’s even more effective than benzoyl peroxide. (7)
The efficacy of Salicylic Acid peels has also been studied, with a couple clinical trials showing a 30% peel used every two weeks significantly decreases non-inflammatory and inflammatory acne (in other words, clogged pores in addition to swollen pimples). (8, 9, 10) Cooler yet, the peels had minimal irritation and caused no changes to skin hydration, pH, and transepidermal water loss (TEWL).
With that said, I would highly advise that newbies DO NOT begin with chemical peels. So chill newbie, chill! That’s for the more experienced users who’ve become accustom to weaker BHAs. ;p
The pH and formulation of SA has a huge impact on how well it works, with study results varying from little difference to 95% of patients seeing improvement. (11)
So again, if your using a BHA that that doesn’t have the proper pH you might be getting little benefit from it other than some anti-inflammatory properties. Sure, that can help some. But to really treat acne, you need to address far more than that.
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Salicylic Acid Treats Hyperpigmentation.
The combination of ellagic and SA produces comparable results to 4% hydroquinone, a potent melanin-inhibiting prescription drug. (12, 13)
BHA is also suitable for darker skin tones, unlike AHA which could cause erythema or worsen hyperpigmentation under the right circumstances. (14) In fact, a study involving 25 people of color showed that 20% and 30% Salicylic Acid peels were effective against melasma and post inflammatory hyperpigmentation by resurfacing sun damaged skin. (15, 16, 17)
The lightening capabilities of Salicylic acid peels has been replicated time and time again, and is suitable for lighter skinned folks too. (18, 19, 20)
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Salicylic Acid Has Anti-Aging Benefits.
SA may have some anti-wrinkle effects. This area has been less studied so take these next couple of studies with a grain of salt. The first, a study involving mice.
Yeah yeah, I already know what your thinking. “Rats? Rats? We’re not rats! How is this relevant to us dude?” I said take this information with grain of salt for a reason…
Anyway, a study involving mice showed that a 30% salicylic acid peel helped rebuild the connective tissue on the surface of skin, thereby reducing wrinkle depth.
As for the people studies — there’s evidence a derivative of SA called sodium salicylate has great anti-aging benefits. (21) It’s made by neutralizing SA with sodium hydroxide (lye), and on three different occasions has shown to significantly reduce wrinkles and skin roughness without irritation, making it a suitable ingredient for those with sensitive skin.
As you may know, sun protection is the most important defense against premature aging. Case in point — see what happened to this trunk driver. Luckily for us BHA doesn’t cause photosensitivity (i.e. increased sensitivity to the harmful effects of sun exposure) like AHAs do. In fact, it may even provide photoprotective properties!
For example, salicylic acid peels have been shown to prevent tumor growth by removing sun damaged cells and reducing carcinogenicity. (22, 23, 24, 25) BHA also inhibits UVB-induced sunburn cell formation, and has been recommended by researchers as a topical protectant against sun damage. (26)
Another study found that using 2.0% Salicylic Acid for 3.5 weeks didn’t increase erythema (redness), DNA damage, or susceptibility to sunburn. (27) The same did not apply to 10% glycolic acid.
Whether the inhibitory UVB benefits apply to Salicylic Acid peels remains unanswered, so err on the side of caution and use sun protection just in case. Wait, scratch that, you should be using sunscreen regardless of what you’re using. Use sunscreen! I’m watching you….
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Salicylic Acid Treats Warts.
WARTS. It treats WARTS. Indeed, in one study 81% of patients were either cured or saw vast improvement after only two weeks of using 26% Salicylic Acid. (28) Other studies have had similar cure rates (about 70%).
A note on the percentage: 26% is chemical peel strength, not something to try out of the blue. If you decide to treat a wart this way, take proper precautionary measures and do your research first!
Side Effects:
BHA may be Irritating, cause dry skin, and if used excessively disrupt the acid mantle. (29, 30) Worst yet, skin that has a damaged moisture barrier absorbs SA more easily which could further exacerbate irritation. As a pair of researchers put it, BHA has “an inherent pH-related irritancy potential which is even more exacerbated on sensitive skin.” (31)
It’s very easy to overdue it with SA. People often have a more is better mentality, but with skincare it’s often the opposite: less is more. The trick is to have the willpower to not jump the gun and play the waiting game. Patience trumps impulsiveness. Skincare isn’t a sprint, but a marathon.
How to Use Salicylic Acid:
Introduce it slowly. Start using it once or twice weekly. The next week increase to three times. The following week, 4 times. Continue doing this until irritation in the form of dry skin, peeling, redness etc. beings rearing its head. The absolute most you should be using it is twice a day.
It’s not uncommon that BHA causes a “purging period” when acne gets worse initially. Don’t fret, this is simply the salicylic acid decongesting what was already there. Depending on how frequently you’re using it, the purging period should last 3-4 weeks maximum before subsiding.
As we’ve discussed earlier SA is pH dependent, so the order of it in your skincare routine matters very much. You want to use it right after cleanser and before moisturizer. Here’s a sample routine with the order of all things being considered.
Note: depending on what you incorporate some of these steps won’t apply to you, so adjust it accordingly.
- Oil cleansing method, or oil cleanser.
- Gentle pH-balanced cleanser (5.5 or below)
- Low pH serums or toner. Wait 20-30 minutes.
- Salicylic Acid (BHA). Wait 20-30 minutes.
- AHA (glycolic, lactic, mandelic). Wait 20-30 minutes.
- Vitamin C (SAP)
- Retinoids (Tretinoin [Retin-A], Retinol)
- Spot treatments or other actives (e.g. Benzoyl Peroxide, Azelaic Acid).
- Moisturizers.
- Occlusives (e.g. Vaseline, Aquaphor)
Product Recommendations:
Because a well-formulated BHA product may be hard to find when you’re just getting started on your skincare journey, here’s a list of products that have the proper pH needed to work.
| Good for sensitive, dry, or dehydrated skin. | Cosrx BHA Blackhead Power Liquid | |
| Good for oily, tough skin. Avoid if you have sensitivities to malassezia! | Paula's Choice Skin Perfecting 2% BHA Liquid | |
| Good for normal to oily skin. | Stridex Strength Medicated Pads |
Alrighty, folks. That does it for salicylic acid. Hope you found this helpful!
Cheers,
—f.c.
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Ok . This answers my question I asked you in the PC BHA post . I was using the Cosrx twice daily . I had zero irritation and only saw a mild flake or 2 on my nose . Face looked like a baby’s but until day 7 . Then Doug started working his way onto my chin . I’m hopping no homies follow . The weird thing is that I really don’t think I had anything to purge out . My pores are the clearest they’ve been since high school. I’ll just take a break for several days . Then I’ll reintroduce BHA twice a week . It was just so damn fun using the Cosrx BHA ! It made my face so soft and glowing . I’m impatient. Gotta slow it down or return to Pazzifacetonfieldville ???? Thanks again !!
I’m impulsive too! Yet another thing we can relate on hahah. But yes, cut back on the BHA to twice or three times weekly and I think you should be fine considering you were already seeing awesome progress. Let me now how it goes! 🙂
Just a heads-up, but a few months ago Silk Naturals reformulated their BHA toner to contain salicylic acid instead of willow bark extract, and it should be at the right pH (3.5-4.0). The ingredients are very similar to their AHA toner which is quite popular for being basic but gentle.
I haven’t tried their BHA myself but thought it’d be worth mentioning so people know they have an option for an alcohol-free, pH-correct salicylic acid exfoliant other than Paula’s Choice and Stridex.
Ahh, nice! I remember the big scene that caused on SCA a couple years back. To be honest, I felt really bad for Karen when that happened. A lot of nasty comments on that thread. Gonna have to try that one now too. Dang it, stop giving me all these recommendations! :p PHA, Paula’s Regular Strength, now Silk Naturals? Lol
Yea, I read the thread you’re referring to and likewise felt a bit bad for her. Maybe that eventually led her to reformulate it with salicylic acid and lower the pH. Her AHA Toner earns a lot of praise — I’ve tried it myself and liked how gentle it was, so wouldn’t mind trying her BHA at some point too. I also like her minimalist, no-filler approach with ingredients — something we dermatitis sufferers have learnt to appreciate.
Oh, also, HER BOTTLES DON’T LEAK. *glares coldly at Paula’s Choice*
I’m just waiting to see what the feedback is from other people before I try it out myself, since the reformulation is still very recent. In the meantime I’d like to try out the COSRX BHA.
Hi. Do you think using bha regularly for years would cause some side effects? Ive been using it hut now I am wondering how salicylic acid gets remived from the body once you applied it topically.
Hi there, Brijette. It shouldn’t be a problem. Salicylic Acid has a very high safety profile, and as mentioned in this article is a naturally occurring substance and necessary component of the human diet. The only thing to be cautious of is its ability to thin the stratum corneum (outer most layer of skin), which could overtime increase your sensitivity to the sun, so make sure you’re wearing sunscreen and all should be good.
Hi! what if i don’t use any toner (sometimes i use a geranium floral water) after cleansing (my cleanser has a ph of 5.5) will the bha still be as effective ?
Hi, Milly. That’s absolutely fine, you don’t have to use toner cleanser.
Hi, f.c. I’ve been binge-reading your site for a week now! Thank you from the bottom of my heart for creating this wonderful blog. I just want to fully understand something about your instruction of introducing BHA for a newbie like me. Does “once a week” really mean only one use (morning or night) for a whole week? Or does it mean one-day use (morning & night) a week? I’m really sorry for this stupid question.
Hi, f.c. I’ve been binge-reading your site for a week now! Thank you from the bottom of my heart for creating this wonderful blog. I just want to fully understand something about your instruction of introducing BHA for a newbie like me. Does “once a week” really mean only one use (morning OR night) for a whole week? Or does it mean one-day use (morning AND night) a week? I’m really sorry for this stupid question.
Also, are you using BHA daily now? How many weeks did it take your skin to get use to it and allow for you use it daily?
I have been using Paula’s choice 2% skin perfecting for over a year and love the results. I use it once a day at night. I always wear sunscreen, but I will be in the tropics in a few weeks. Should I stop the BHA prior to traveling and all the sun exposure I will get? Just don’t want to do anything that might result in skin damage or irritation.
Hi there, Wendy. Salicylic acid doesn’t cause sun sensitivity, and in fact, might protect against UVB induced erythema. I don’t think you have anything to worry about. I just went on vacation myself and used a DIY BHA exfoliant the entire time! :p
Hi there! I would like to know that does that mean cleansers that contain Salicylic Acid are actually…pointless? Since most of them don’t have pH as low as 4, and one of the low pH cleansers that contain Salicylic Acid (Betaine Salicylate) which is CosRX Low pH Good Morning Gel Cleanser also has a pH of 5 (should be higher if mixed with water I guess).
Does “purging” would still occur in this case?
Thank you in advance!
Hi there, Dickson. If the pH isn’t below 4, yes they’re pretty much useless aside from the anti-inflammatory properties BHAs provide. There’s actually some evidence that betaine salicylate works at higher pH, so purging might be a symptom.
For those who still don’t have much success with salicylic acid, I think mandelic acid is a viable alternative worth mentioning here (or maybe in a separate post someday). As far as the hydroxy acids go I think it’s the most versatile. It’s an alpha-hydroxy-acid, but it’s unique among the AHA’s in that it’s partially lipid-soluble (although not as lipid-soluble as salicylic acid), so it does a bit of what a regular AHA does, and a bit of what salicylic acid does, and yet is gentler than both due to its larger molecular structure, which means it penetrates the skin more slowly and the exfoliation is more evenly distributed.
Another big selling point is that from the research I’ve looked into, it has a much stronger antibacterial effect against p.acnes than salicylic acid (which I believe is very weak as an antibacterial), and so many people might find it more effective for acne. So in that sense, it’s kind of like an AHA combined with a BHA combined with an antibacterial (like benzoyl peroxide, azelaic acid, etc.), all in one, and yet gentler than all of the above. What’s not to love?
The only downside is that, like all AHA’s, it does increase the skin’s sensitivity to the sun, but if you’re in the habit of regularly using sunscreen (as everyone should be) then this isn’t a concern.
My research led me to mandelic acid in particular after following the same path that had led me to PHA’s like gluconolactone — i.e., seeking out actives that are very effective but with minimal or no side effects like irritation, dryness, etc. The main benefits that mandelic acid has over PHA’s, for now, are that it has more product choices available and there’s a fair bit more research into its activity against acne. Alternating between both might become a staple of routine, once a suitable PHA product becomes available (or I finally have the confidence to formulate my own).
Do you find the different versions of the Paula’s Choice BHA to be less drying? I know they have the regular strength and the gel… do you have any experience with those?
What are your thoughts on Paula’s choice’s higher concentrations of BHA such as the 4% and 9%? I used to use the 2% lotion type daily, then I switched to the 4% 1-2 times per week. I feel like my skin has built up an SA tolerance and its not as effective anymore, could that be true? I have been contemplating getting the 9% and using it once a week.
hi! Thank you for your wonderful blog. I am from Austria and it is difficult to get the products you recommend, for example I would like to buy the stridex pads or the cosrx products but they are not availlable, the only availlable products are some paula’s choice products on amazon. Is there any other product with bha you would recommend for malassezia acne?
Hi. I just wanted to ask. I am using the neutrogena blackhead eliminating toner. It contains BHA(Salicylic acid) as well as gylcolic acid. Is it safe for me to use it twice everyday? And did i still need to use scrub to exfoliate my skin?