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I, by no means, am claiming to be an expert in dermatology. I’ve done my best to be as thorough as possible during my research. If you’re an expert and find an inaccuracy, please let me know and I’d be happy to investigate. This is a learning experience for me too.
Lemon Juice in Skin Care
After countless hours browsing Pinterest, I’ve seen so many DIY skin care recipes calling for lemon juice. These recipes claim various skin lightening and acne fighting benefits. I was particularly intrigued by the latter – an inexpensive, easily accessible way to clear up acne? Sign me up! But wait – hold your horses. Prior to trying out these recipes, I thought I’d do a little investigating about the efficacy (and safety) of using lemon juice on skin. Here’s what I found out.
Claimed Benefits of Lemon Juice
It’s actually pretty logical to assume lemon juice is good for the skin. (And no, one of them isn’t that lemon juice is chemical-free – everything is made up of chemicals!!!!). Chemicals found in lemon juice impart various benefits to skin:
- Anti-aging: Lemon juice contains vitamin C (a.k.a. ascorbic acid) and citric acid which, when applied to skin, have been claimed to have anti-aging properties.
- Acne-fighting: Various studies have found that lemon juice is an excellent antimicrobial (i.e. killer of germs), especially when used in combination with honey. Antimicrobial properties are especially helpful for combating acne. Presumably, lemon juice’s antimicrobial activity is due to its highly acidic nature (around pH 2 – more on pH shortly), thanks to the presence citric acid.
- Skin Pigmentation: Vitamin C has been shown to reduce dark pigmentation in skin. It does this by decreasing melanin formation (melanin is a brown pigment responsible for skin colour). Thus, it’s effective in reducing scarring, sun spots, and age spots, which all involve excess melanin.
Evidently, lemon juice definitely contains some chemicals (e.g. vitamin C, citric acid) that seem promising for improving skin! And to be truthful, these individual chemicals themselves are effective and safe. But using pure lemon juice itself? Not so much.
Why You Should Probably Avoid Lemon Juice
The concentration of active ingredients in lemon juice differs depending on where the lemon was grown, ripeness, post-harvesting handling and storage conditions, etc. Thus, lemon juice cannot guarantee a consistent or efficacious amount of active ingredient delivery.
If you’ve read my Skin Basics article, you’ll know that skin has a thin, acidic film called the acid mantle. This makes it such that the skin is slightly acidic, with a pH of around 5. Proper maintenance of the acid mantle is crucial as it creates an environment that supports proper functioning of the skin barrier. (Thus preventing dry skin and infections). In other words, chemicals responsible for forming the protective skin barrier function optimally around pH 5.0.
The skin is pretty good at recovering from changes in pH. However, when skin pH is changed too drastically (as is the case with pH 2.0 lemon juice), it takes much longer for the skin to normalize back to pH 5.0.
The difference between pH 2.0 and 5.0 doesn’t seem that drastic, right? pH 2.0 is just like, 3 times more acidic than 5.0? Nope! pH is a logarithmic scale. This means that pH 2.0 is actually 1000x more acidic than pH 5.0!
As a result, pure lemon juice can easily cause skin irritation (redness, stinging, etc.). While there are many studies on the effect of higher pH on skin barrier function, studies are lacking regarding the effect of lower skin pH (as is the case with lemon juice) on skin barrier function. Thus, I’m unsure as to whether strongly acidic pH substances would disrupt the barrier, however they can definitely cause irritation.
Sun Sensitivity and Burns
Phytophotodermatitis is a condition that can result after the skin is exposed to certain chemicals in plants, and then exposed to sunlight. In the case of lemons (and limes), they contain phototoxic chemicals called furocoumarins. When exposed to UVA light, furocoumarins cause reactions in the skin that lead to swelling, blisters, and redness. Basically, leaving lemon juice on your skin makes your skin extremely sensitive to sunlight.
Still Not Convinced?
If you’re still not convinced that you shouldn’t be using lemon juice on your skin, here are some things you can do to minimize skin damage:
Apply lemon juice mixtures at night
To minimize risk of phytophotodermatitis, apply lemon juice mixtures at night. If you absolutely have to apply it in the morning, ensure to use (and continue to reapply throughout the day – because sunscreen only works for like maximum 2 hours after application) sunscreen that includes protection from UVA and UVB light (some sunscreens only protect against UVB light – look for Broad Spectrum or UVA/UVB labels).
Also, the furocoumarins in lemon juice must be absorbed into the skin before it can sensitize skin to sunlight. This process takes anywhere from 30 to 120 minutes, so adequately cleansing the skin of lemon juice with water prior to absorption can help prevent phytophotodermatitis.
Dilute or neutralize lemon juice to decrease strong acidity
Do note that if you dilute lemon juice (e.g. with water), you’re effectively reducing the concentration of vitamin C and other beneficial active ingredients. Efficacy of vitamin C is proportional to its concentration (up to a maximum of 20% vitamin C concentration, after which efficacy doesn’t increase with concentration). In other words, the lower the concentration of vitamin C, the less effective it’s going to be.
Also, vitamin C is only active and stable at pH’s less than 3.5. If you neutralize the lemon juice (e.g. by adding a basic chemical like baking soda), you’re likely raising the pH too high, such that the vitamin C is no longer active. But, it will be less irritating to the skin if the pH is around 5. (i.e. not irritating, but also not doing anything for the skin due to inactive active ingredients).
The Bottom Line
Many people have reported reduced acne and scarring while using lemon juice. However, while lemon juice may be moderately efficacious, I think the side effects far outweigh potential benefits. Every time I see a skin care recipe calling for lemon juice on Pinterest, I die a little bit inside. ;-;
If you’re looking to reap some of the benefits of the active ingredients in lemon juice, I recommend trying a vitamin C serum, which have been proven to be highly efficacious and much safer. Vitamin C serums are specifically formulated for skin and good serums will be properly pH-adjusted to ensure vitamin C is active and available to the skin, while minimizing harsh acidity.
Since I’m also interested in learning more about vitamin C serums, I’ll have a post coming at some point that delves into these serums. After I’ve had the opportunity to test a few myself, of course!
Thanks so much for reading. I hope it was helpful and hopefully you learned something. If you have experiences with lemon juice in skin care (good or bad!), I’d love to hear about it in the comments below, or you can contact me!
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