Did you know that the cause of pimples is actually unknown?

Whether it’s painful nodule cysts, blackheads, whiteheads, or those little red bumps, the medical community still doesn’t know what causing them.

Sure, they know that each is the side effect of a pore collapsing on itself and blocking the sebum (oil) from coming out, however they still don’t know why that happens in the first place.

Hormonal changes are an obvious possibility, as are nutritional deficiencies/poor diet, stress, inflammation, infections, and genetics (it often runs in families). There is good evidence both for and against each of these causes. (1)

Because we don’t know for sure the exact root cause(s) of this skin disorder, treating it is all the more challenging.

From antibiotics to Accutane that you get at the dermatologist, to bizarre and unproven at-home remedies, you have people claiming everything under the sun can help (or hurt) your acne cysts.

When it comes to this golden liquid, what are we to believe?

5 scientific reasons why ACV may help pimples

Whether you drink it or apply it topically to your skin, there is no proof that it works for this. In fact, there hasn’t even been human studies evaluating vinegar specifically for pimples, blackheads, or whiteheads.

With that said, there is science to support the possibility that it might not be a scam after all. The strongest cases can be made for the following 5 ways it may work.

1. Inhibits P. acnes bacterial overgrowth

Propionibacterium acnes (P. acnes) is a type of bacteria that is naturally found on your skin.

As you can probably guess, the reason it was given that scientific name was because overgrowth of P. acnes was found to correlate with acne vulgaris.

stages of how acne forms

By OpenStax College [CC BY 3.0]

While it can be a worsening factor – especially with redness and inflammation of the closed pores – it’s not believed to be a root cause. With many cases of acne, overgrowth of it is not an issue and furthermore, other types of bacteria like Staphylococcus and Corynebacterium are also found on the skin and can exasperate closed pores in the same way. (2)

These and other bacteria feast off your skin’s sebum. They eat the oil (triglycerides) in it.

Antibiotics are believed to work, at least temporarily, by reducing the overgrowth of P. acnes and other bacterial strains on the skin. The problem is that this benefit is short lived, as the bacteria becomes resistant to tetracycline, doxycycline, and others over time.

Antibiotics are typically just a “Band-aid” fix of a few months for acne on face or back.

difference between gram positive and gram negative bacteriaP. acnes is a type of gram-positive bacteria.

Basically that means P. acnes has a very thick cell wall. It also means it’s harder to kill with topical treatments.

The over-the-counter topical treatments use benzoyl peroxide and/or salicylic acid as their active ingredients. This does kill off P. acnes though over time, however as with antibiotics, these treatments also have a diminishing benefit.

Being that apple cider vinegar is a corrosive acid, it’s feasible that using it in the form of a face mask or body wash might help with excessive bacterial overgrowth of P. acnes and others.

Unfortunately there’s no formal research on using ACV in vivo (in human subjects) to see whether this hypothesis holds true.

However there is other evidence for vinegar applications.

In a study out of India, 40 female patients were given an herbal vinegar formulation to apply once daily at night for 15 days, followed by usage every other day for another 15 days. The results were (3):

  • 6% reduction in tenderness
  • 9% in itching
  • 6% in irritation

Less irritation and tenderness may also mean milder scarring, after a pimple has run its course.

2. Promotes optimal pH of skin

The concept of an alkalizing diet is confusing.

Vegetables, fruits, and vinegar made from apple cider are acidic on their own. Yet when we eat them, they have an alkalizing effect (the opposite of acid forming) after they are digested.

acid-forming vs. alkaline-forming foods

To understand this better, read the lowdown on apple cider vinegar benefits.

Does drinking apple cider vinegar help acne?

Probably not, at least in relation to it affecting the pH of your skin. You would have to consume massive amounts of vinegar to sway you body’s natural pH, which is between 7.3 and 7.4. Even then, you may only alter it 1/100th of a point. Your acid-base homeostasis would restore the pH to its natural number shortly thereafter. (4)

When applying vinegar topically to the skin, the answer is different. It will create a more acidic environment, at least for a while.

Unlike inside your body, which you don’t want overly acidic, science has found that our skin is naturally more acidic. Or at least it’s supposed to be.

Recent research (2017) has found that the microbiome of your skin, when properly balanced, helps to maintain a more acidic pH.

This increased acidity helps defend against infections from bad bacteria and other pathogens, like fungi and viruses.

Ironically, it’s the right strains of Propionibacterium acnes and its close relative, Propionibacterium granulosum, which can help to promote the ideal acidic skin environment for fighting off the bad guys.

In this study, they found that the skin microbiome of acne sufferers were more likely to have the bad strains of P. acnes, while those without acne had the helpful strains. (5)

So what does all this have to do with ACV?

Perhaps nothing. However if you take the premise of their results, which is that an acidic skin environment can be good for acne, you can extrapolate from that. Hypothetically speaking, using ACV as a toner may benefit acne by promoting higher skin acidity.

Of course it’s worth mentioning that this theory doesn’t mesh perfectly with  the first reason. If some types of P. acnes in the right balance are healthy and the vinegar kills them, then it might actually worsen your breakouts.

3. Exfoliates dead cells and excess sebum

using facial skin careThis benefit is rather straightforward and non-controversial.

Acids have a keratolytic effect, which means they can cause the outermost layer of skin to loosen and this helps with the shedding dead cells. In turn, that can limit the amount of debris that is there to clog your pores.

The keratolytic effect is one of the acne benefits of salicyclic acid, as well as retinoids like Retin-A Micro, Differin gel, and Tazorac. (6) (7)

Exfoliation can also boost the rate at which your skin cells replace themselves. This can help diminish acne scars faster.

Without human clinical studies, no one can say whether or not apple cider vinegar is better or worse at exfoliation than other keratolytic agents in dermatology. Though it is a natural acid that likely has at least some effect when used topically on the skin as a toner.

4. Supports healthy gut flora

front page of 1930 study on acne prevalence and low stomach acidProbiotics are mostly touted for digestion but scientists are starting to realize our gut microbiome affects a lot more.

You may assume this is some new age scam, but the theory that gut flora influences acne dates back at least to the 1930’s.

In that year, two men from the Department of Dermatology at the University of Pennsylvania published research documenting two years of clinical observations on gastric secretions and how they seemed to correlate with different diseases of the skin, such as eczema and acne. (8)

They found that 40% of those with acne also had low stomach acid (hypochlorhydria). Based on that, they hypothesized that too little acid allows for bacteria from lower down in the digestive tract to make its way higher up – from the colon to the small intestine – and this would interfere with a healthy intestinal flora.

Interesting in that it sounds a lot like small intestinal bacterial overgrowth (SIBO) whose awareness and diagnoses are surging in recent years.

The next study was in 1955. They found that acne sufferers generally had the same bacterial profile in their gut, except there were more of the Bacteroides species. (9)

In 2001, Russian doctors measured the levels on 114 people with mild to moderate inflammatory (papulopustular) and cystic (nodulocystic) types of acne. 54% of them (61 people) had an “impaired bacterial microflora.” When they took probiotics, it seemed to help reduce their pimples. (10)

On related note, differences in gut flora have been seen with other skin diseases too, like atopic dermatitis/eczema. (11) (12)

Here’s where this vinegar may play a role…

Does ACV increase stomach acid?

If boosting stomach acid really does help thwart SIBO and other bacteria growing too high in the intestines, it’s unlikely that cider vinegar or others can help by altering the stomach acid levels.

pH scale

Vinegar is extremely weak relative to your stomach acid, so even a temporary altering of the pH probably does not occur. Even though ACV may only be a number or two higher on the pH scale, keep in mind that it’s like the Richter scale for earthquakes, where each number is exponentially higher than the last.

This means that drinking ACV straight from the bottle would still be like a drop in the bucket compared to the pH of your stomach acid.

Does ACV affect probiotics?

diagram for steps of how apple cider vinegar is madeCider vinegar is made by combining crushed apples and yeast, then allowing them to ferment. During this process, bacteria do multiply and that includes several beneficial (probiotic) strains; acetobacter, lactobacillus, oenococcus, komagataeibacter, gluconobacter. Very little remains after fermentation.

Organic and unpasteurized varieties will be more likely to contain these living organisms. (13)

This diagram shows you how the highest levels of probiotics are found during the first fermentation, before the final apple vinegar is made.

There is “the mother” which is that cloudy blob in the bottle of Bragg’s, but that doesn’t necessarily mean any living probiotics are in there.

The good news? Whether or not there are living probiotics may not even matter!

Regardless of whether it’s raw and unpasteurized, as long as its unfiltered and contains “the mother” then there is at least some pectin inside.

Pectin is a non-living matter. It’s a type of plant fiber that serves as a prebiotic – meaning it’s food for probiotics in your intestines.

Prebiotics resist gastric acidity in the upper digestive tract (i.e. stomach) and make their way to your intestines, where they are fermented by the microflora. Prebiotics like pectin can stimulate and promote the growth of the bacteria that are already there. (14)

In many ways, prebiotics make more sense than taking probiotic supplements. No one knows if the latter are even living and if they are, is it really a good idea to be introducing them at the top of the GI tract, where they might actually cause bacterial overgrowth?

By using prebiotics, you are feeding your body’s probiotics in the area they are naturally found. You’re not introducing probiotics to areas they shouldn’t be – your stomach and upper intestines.

The human studies are far too preliminary to know whether or not the balance of gut bacteria helps or hurts acne. If it does play a role, then it’s certainly feasible that prebiotic sources, such as apple cider vinegar, may help by supporting your body’s naturally-occurring probiotic colonies.

5. Reduces insulin and IGF-1 levels

Insulin-like growth factor 1 (IGF-1) is a hormone produced by the liver. As the name suggests, it’s “insulin-like” in structure, but is not actual insulin.

What does IGF-1 do in the body?

  • Mediator of the growth hormone (GH)
  • Interacts with insulin in the metabolism of carbs

Without IGF-1, a type of dwarfism occurs (Laron’s syndrome) so it’s obviously important, but excess amounts or wild fluctuations can wreak havoc on your hormone levels and worsen acne.

Research out of Israel involving 21 patients with Laron’s syndrome discovered the following (15):

“This study demonstrates for the first time that serum IGF-1 deficiency prevents the occurrence of acne. The findings suggest that an interaction between IGF-1 and androgens is necessary for the development of acne.

That makes sense, because it is well-established that high insulin (which accompanies high blood sugar) and high levels of IGF-1 can worsen hormonal-related acne.

Research has reported that (16):

“The highest concentrations of IGF-1 are found in women with acne and the number of acne lesions positively correlates with the plasma levels of IGF-1”

High insulin, which goes along with eating high-glycemic foods, also worsens it (17):

“In brief, one prospective cohort study found an association between high-glycemic-index foods and longer acne duration, whereas two randomized controlled trials associated low-glycemic-index diet with reduced acne risk.”

There are multiple reasons why IGF-1 and high insulin levels can worsen this skin condition:

  • They stimulate the production of more sebum (oil) in the skin.
  • They spur the release of DHEA, which is the precursor to numerous hormones.
  • They affect the conversion of androgen precursors into testosterone and DHT.

Confused? Just know that high levels of insulin and IGF-1 screw with your hormones.

That’s why high levels of both can be bad for hormone-related acne, which is the same type that many teens and young adults experience.

What does vinegar have to do with all this? Several studies have found it to have a lowering effect on blood glucose and insulin levels.

As published in the Journal of Diabetes Research, a human study out of Greece evaluated levels with and without vinegar consumption in 11 people with type 2 diabetes.

They consumed 30 mL of vinegar, with 20 mL of water added so it was safer to drink. Or they were given 50 mL of plain water.

graphs showing blood sugar and insulin levels with and without vinegar consumption
After eating a meal, levels of blood sugar and insulin were lower when vinegar was consumed. (18)

The type used in that study was not specific to apple cider, though several other studies have used it.

As published in Diabetes Care journal, put out by the American Diabetes Association, 20g of ACV was pitted against a placebo of 40g of water and 1 tsp of saccharine. The measurements were taken after eating a high glycemic meal.

charts showing insulin and glucose levels in healthy, pre-diabetics, and diabetics after drinking 20g of vinegar

The controls were healthy non-diabetics (8 people), insulin resistant (11 people), and type 2 diabetics (10 people).

In all 3 groups, the lowest bars with the open squares on them were for vinegar, while the higher lines with the solid black circles were for the placebo drink. (19)

There are other studies, too. Apple cider vinegar and honey was found to have the opposite effect; it increased fasting insulin levels. That’s bad, so avoid the honey-sweetened versions! (20)

There is still not enough evidence to prove the benefits of lowering insulin and IGF-1. It it is happening, it would be a logical explanation of how drinking apple cider vinegar everyday for acne could be helpful.

And if it is happening, no one knows how it works. Theories put forth are that it may slow gastric emptying (and therefore digestion), may improve satiety (so less food eaten), and may increase insulin sensitivity.

Side effects

enamel damage from acid vinegar

The 15 year old’s front teeth with severe erosion of the buccal surfaces

Chemical burns when used topically and esophageal injury when drank are some of the risks that come with using apple cider vinegar. When not adequately diluted in water, permanent erosion of tooth enamel can occur.

Toners and masks on both the face and body become more dangerous if the vinegar is left on for extended periods of time.

Some internet tutorials give instructions of leaving it on for one hour or even overnight, both of which are dangerous and dramatically increase the odds of chemical burns and scarring that may result from them.

The photo here was taken from a case-study of a teen who was drinking vinegar for weight loss daily. The dentists determined it caused permanent erosion in her teeth. (21)

How to use ACV for acne

If you are under the age of 18 you should only try this remedy with the permission and guidance of your parent/guardian.

Whether you are young or old, it’s also important to consult your doctor first if you will be drinking it, since doing so may interfere with certain medications and/or affect hormonal balances.

1. Buy an organic and unfiltered variety

Bragg ACV bottleFor drinking it, there is stronger evidence to support the use of raw, unpasteurized, and organic apple cider vinegar. That’s what was used in the study which measured probiotic content.

If the vinegar is filtered, it will contain much less pectin, which is the prebiotic substance in the cider.

Of course Bragg is the most well-known brand, but there are plenty of comparable options for sale today the are unpasteurized and unfiltered.

2. Do not mix vinegar with honey

Some bloggers advise ACV and honey. Contrary to popular belief, honey is a high glycemic sweetener. When it’s used internally or externally, this added sugar only has the potential to hurt – and not help – levels of insulin and IGF-1.

3. Dilute the vinegar thoroughly before drinking

Since it has up to 5% acidity and sometimes even more, you should never drink pure vinegar of any kind. In order to avoid damage to the teeth, mouth, and esophagus, dilution with water or another non-acidic liquid is necessary.

diluting 1 tbsp of apple cider vinegar in 1 cup of water

Even though some sources recommend a 50/50 mixture, a 9:1 ratio is safer. To accomplish this, add 2 tablespoons of cider vinegar to one cup (8 ounces) of water.

4. Start by drinking it only once per day

If consuming 2 tablespoons of vinegar with 8 ounces of water, starting out this should only be taken once daily.

While experienced users may be drinking this amount on 3 separate occasions spread throughout the day, it’s important to start with a lower amount until you know how your body will respond.

5. For topical treatments, dilute with water and dab with cotton ball

Undiluted vinegar is particularly dangerous on the face, as your eyes and mucous membranes are at increased risk.

Whether it’s the face or body, you should dilute the ACV with at least a 1 to 1 ratio of water. To start out, more dilution is recommended; 2 parts water and 1 part vinegar.

male using cotton ball soaked in cider vinegar on facial acne

To control the application, make this mixture in a small glass, dip a cotton ball in, and use that to wipe your skin. If you have fresh acne scars, avoid contact with them as the vinegar may slow their healing, or even irritate them to the point of re-bleeding.

Even when it’s diluted, never pour vinegar directly on your skin as it will be too hard to control where it ends up. Never apply on or near your eyes, nostrils, lips, or ear canals.

6. Leave on skin for the optimal amount of time

After you have applied the diluted vinegar to your skin using a cotton ball, how long should you keep it on before rinsing?

User reviews have reported success with anywhere from 1 to 30 minutes, before rinsing the application. When it’s left on for 10 or more minutes, it will usually dry to the touch.

Starting out, it would be best to only use it for 1 minute before rinsing. Even experienced users may not be able to keep it on longer than a few if they have sensitive skin.

Never leave it on for hours or go to bed with it on your face or back.

7. Don’t use with benzoyl peroxide or other acne creams

tretinoin cream tubeBenzoyl peroxide, salicylic acid, and glycolic acid are all over-the-counter treatments which in and of themselves can burn your skin. It may be unsafe to combine them with topical ACV treatments, as doing so will increase the risk of skin irritation and burning.

Never combine with prescription topical skin treatments, such as Retin-A or generic tretinoin cream. If you are on any, consult your dermatologist before trying vinegar as a skin toner.

The verdict

Since there are not adequate studies done, no one can claim it cures acne or even helps it. There isn’t yet proof. Much of what you see online about this topic is pure hype and not even based on science!

That said, there is real scientific data to suggest it might work. If these theories are true, it may take some time to see results.

How long does it take for apple cider vinegar to work on acne?

If you are drinking the diluted vinegar in hopes of it lowering insulin and IGF-1 levels, it may take up to 1 month of daily consumption to see an improvement in your breakouts. If using ACV as a facial toner, the exfoliation effects would start on day one, however it would likely take at least 10-14 days until clearer skin becomes noticeable.

To reiterate, these timeframes are only hypothetical “best guess” estimates based on preliminary published data and user reviews. Remember, drinking and/or using topical treatments are unproven remedies.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.