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There are more DIY skincare recipes on the internet than you can shake a stick at, and most of them really, really like lemon juice. According to these DIY tips you should be slathering it all over your face and hair. Lemon juice smells nice, and it’s pretty cheap. But is it effective? And is it safe? Let’s talk about the science behind lemon juice.

Here’s the video version – keep scrolling down to read!

Is it effective?

Lemon juice contains a lot of ingredients that are used in skincare:

• Vitamin C: Lemon juice contains vitamin C in the form of ascorbic acid. Vitamin C does a great job at evening out pigmentation without too much irritation, and could help increase collagen in your skin as well. It’s also an antioxidant that counteracts free radicals, making it good at protecting your skin from the sun.
• Citric acid: Citric acid is an alpha hydroxy acid (AHA). You can read more about AHAs in skincare here, but in short they’re great for exfoliating your skin, making it look plumper and smoother.
• Niacin (vitamin B3): This is anti-inflammatory, helps with pigmentation and alleviates dry skin as well. More about niacinamide here.

Related Post: How to Get Glowing Skin: All About Exfoliation (Video)

So yes, lemon could be great for your skin! But before you rub a lemon on your face, there are a few issues with using lemon juice…

How strong is a lemon?

Not only do you need a skincare product to have effective ingredients, you also need skincare products to have enough of each effective ingredient. This is also known as the dose-effect relationship – the smaller the dose, the smaller the effect, until at some point you have so little that there’s no effect.

Since lemons are natural ingredients, the amounts in them can vary. You know how different varieties of apple can taste completely different? Or how different brands of apple juice look and taste different? Or how an unripe banana is nothing like an overripe banana? That’s because they contain different amounts of chemicals in them.

Related Post: Are Natural Beauty Products Better? (Video)

This is exactly the same for lemon juice – the amount of each good ingredient in your lemon will depend on all sorts of things, like where it was grown, the time of year, how long it’s been sitting around for, the variety of lemon, whether the lemon was kept refrigerated or at room temperature after picking… there’s no guarantee that you’ll be able to replicate a recipe.

But in a typical sample of lemon juice, you’ll find 0.04% ascorbic acid, 5% citric acid and 0.0001% niacin.

Normally in skincare, serums will have 5-15% ascorbic acid, 2-15% AHA, and 2-10% niacinamide. So in lemon juice, you only really get a decent amount of citric acid.

Is lemon juice safe?

Onto the more important question: is lemon juice safe to use in skincare? Unfortunately, the answer is… probably not. While food might feel benign since we eat it all the time, it’s often a different story if you try to use them in skincare. There are millions of other chemicals in lemon juice, and some of these are not good for your skin.

Phytophotodermatitis

The citrus fruit peels often contain chemicals called furanocoumarins and psoralens. These are fine in the shade, but if you get them on your skin and then go into sunlight, they turn into nasty skin irritants. There are many stories of people who have gotten lemon juice on their skin and gone into the sun – the result was nasty blistering burns!

You can tell how common it is from all of the reports in the literature of this happening with citrus juice.

These phototoxic compounds can be removed from citrus essential oils by processing though, and a few don’t contain these at all (e.g. tangerine), so not all finished products containing citrus need to be avoided. But there’s no easy way to separate them if you DIY!

Chemical Leukoderma

DIY lemon juice skincare has also been linked to chemical leukoderma, where patches of skin depigment – in other words, you end up with uneven lightened patches on your skin.

For example, this article has photos of what happened to one woman who tried using a lemon juice toner – instead of evenly fading pigmentation, the lemon juice faded it in patches, leaving spots everywhere.

Another person ended up with depigmented patches after using lemon juice on their face for 5 days.

It’s not entirely clear how exactly lemon juice does this – it could simply be the low pH of 2, which is lower than pretty much all skincare products except peels, which are applied carefully and neutralised, instead of being left on skin.

Lemon isn’t even that cheap

Lemon might seem cheaper than a properly formulated skincare product, but it turns out it isn’t even that cheap.

Citric acid is the only active ingredient in lemon juice that’s in a high enough concentration to do anything. But it’s actually cheaper to go out and buy pure citric acid and dissolve it in water. A jar of citric acid is $2.25 for 75 g. To get the same amount of citric acid from lemon juice (assuming that a lemon containing 30-45 mL of lemon juice with 5% citric acid costs $1.78), you’d be paying $60-89.

I still wouldn’t recommend making this DIY serum. While this would avoid the blistering photodermatitis, it won’t necessarily help you avoid chemical leucoderma (since the pH is still quite low unless you adjust it). And because citric acid is quite a large molecule, it’ll work better in a properly formulated product that’s designed to help the citric acid penetrate through your skin.

It’s hard to compare against properly formulated AHA products, since very few of them use citric acid at all, and the formulas are quite different (different percentages will have different effects, and they often contain other beneficial ingredients too, and the effectiveness of the formulations will vary).

But if we do a very rough comparison, for the same number of acid molecules (1 mole):

• • 1 lemon (5% citric acid, $1.78 for 30-45 mL) = $152-228 per mole

• • KraveBeauty Kale-lalu-yAHA (5.25% glycolic acid, $25 USD = $35 AUD for 200 mL) = $254 per mole
  • The Ordinary Glycolic Acid 7% Toning Solution ($14.50 for 240 mL) = $66 per mole
  • The Ordinary Lactic Acid 5% + HA 2% ($12.40 for 30 mL) = $794 per mole
  • The Ordinary Lactic Acid 10% + HA 2% ($12.70 for 30 mL) = $407 per mole
  • Pixi Glow Tonic (5% glycolic acid, $28 for 100 mL or $45 for 250 mL) = $274-426 per mole
  • CosRX AHA 7 Whitehead Power Liquid (7% glycolic acid, $25 for 100 mL) = $272 per mole
  • Acne.org AHA+ (10% glycolic acid, $26.33 for 177.42 mL or $46.49 for 473.12 mL) = $75-113 per mole
  • Paula’s Choice 8% AHA Gel (glycolic acid, $39 for 100 mL) = $371 per mole

So not only are there lots that are comparable in price to lemon juice, there are actually a couple of finished products that end up being cheaper than lemon juice in terms of AHA molecules you get! And you have the added of being safe, and having a delivery system that’s more likely to work.

Lemon isn’t always unsafe

While it’s incorrect to say that lemon juice is always unsafe in DIY recipes, there are enough scary stories to make you think twice!

If you still want to use lemon juice after all this:

• Don’t use leave-on recipes with large amounts of lemon juice (more than a few drops)
• Be cautious when using lemon juice for rinse-off recipes (e.g. masks or hair rinses), especially if there’s a large amount of lemon juice in it, and make sure you wear sunscreen next time you go into the sun.
• Stop immediately if you see any signs of irritation or depigmentation!

Further Reading

Hankinson A, Lloyd B & Alweis R, Lime-induced phytophotodermatitis, J Community Hosp Intern Med Perspect 2014, 4, 25090. DOI: 10.3402/jchimp.v4.25090

Almeida HL Jr et al., Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis, Clinics (Sao Paulo) 2008, 63, 371-4. DOI: 10.1590/S1807-59322008000300014 

Gye J et al. Chemical leucoderma induced by homemade lemon toner, Australas J Dermatol 2014, 55, 90–92. DOI: 10.1111/ajd.12133

Kumar K et al. Contact leucoderma caused by lemon, Indian J Dermatol Venereol Leprol 1996, 62, 61. PMID: 20947980

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