Have you ever seen a TikTok telling you to rub garlic and lemon juice on your face? Have you ever tried to treat your acne with toothpaste and baking soda?

If so, you’re not alone. I have washed my face with raw garlic, applied vinegar to pimples, and rubbed cherries on my skin—all of which only resulted in severe irritation. A few months ago, an onion juice hair mask and a homemade shampoo irritated my scalp so badly that clumps of hair fell out and my entire scalp burned for days. Luckily, after a visit to a dermatologist, I was able to address the underlying issue. My main takeaway? Natural, at-home remedies are not always better.

DIY to go viral

The number of DIY skin-care recipes on the internet is overwhelming. With hacks that include everything from cucumbers for puffy eyes to period blood for better skin, it can be challenging to decide what could be helpful and what could be harmful.

It’s important to remember that most people giving skin-care advice on the internet are, well, not qualified to be giving skin-care advice. “There is a lot of misinformation on the internet,” says Geeta Yadav, MD, a board-certified dermatologist and the founder of FACET Dermatology in Toronto. “Plenty of people have their hearts in the right place, but many will do whatever it takes to go viral.” If a skin-care trend you see on TikTok, YouTube, or someone’s personal blog seems outrageous, it probably is. Let’s dive into a few of these issues.

Are preservatives really harmful?

A lot of people turn to DIY solutions out of a fear of harmful ingredients in skin-care products. While it’s definitely a good idea to research the products you’re using, some ingredients that are widely considered harmful simply have a bad reputation.

Take preservatives, for example. “Preservatives are not inherently harmful,” says Dr. Yadav. “Most preservatives that people shun are shown to be safe in the levels used in beauty products; there are also plenty of safe preservatives that are used in beauty products, such as propylene glycol and sodium benzoate.”

In fact, preservatives are necessary to make sure that beauty products remain safe to use over time. According to Dr. Yadav, not using preservatives is more dangerous: “Preservatives are used to prevent the proliferation of bacteria in beauty formulas, which are perfect breeding grounds for microbes, especially liquid formulas,” she says.

“It’s really important that we push people away from the idea of preservative-free,” Nneka Leiba, deputy director of research for the Environmental Working Group (EWG), previously told Well+Good. “What we really want to see is innovation and testing to find newer preservatives that are safer.”

DIY recipes usually don’t include preservatives, which means that your product—whether it be a homemade shampoo, aloe vera juice you have squeezed yourself, or a facemask you’re storing in your fridge—can quickly expire and become prone to causing irritation.

Natural ingredients are powerful too

Due to this widespread fear of what people often refer to as “harsh chemicals” in lab-produced products, many will turn to natural ingredients, thinking they are safe alternatives.

But just because an ingredient is “natural” does not mean it can’t be potent. “People think that ‘natural’ is better, but I always remind them that things like cyanide and arsenic are natural, too,” says Dr. Yadav.  DIY skin-care recipes often include ingredients that are highly acidic, such as lemon juice, vinegar, and garlic, to be applied topically to the skin. Some recent trends include lemon juice to brighten armpits and coffee grounds to fight signs of aging.

Acidic ingredients can cause severe irritation. “Especially in high quantities for extended periods of time or on sensitive skin,” Dr. Yadav says, noting that acidic ingredients can lead to chemical burns. Instead of dabbling with potentially harmful natural ingredients, it may be better to choose products that have been formulated and tested in a lab.

Every remedy has its caveats

The style and tone of internet DIY trends are often along the lines of, “Here is this amazing remedy that will cure your ailment 100% in no time at all and with minimal effort.” But the reality is that skin and hair care needs are complex, highly individualized, and depend on many different factors.

As an added complexity, every skin and hair care remedy, whether natural or lab-produced, has caveats. Dr. Yadav says that mayonnaise and coconut oil can be great conditioning treatments for hair and that castor oil can promote hair growth. “But if you are prone to dandruff or seborrheic dermatitis,” she warns, “oils can make it worse.” Not every remedy will work for everyone, in the same way that not every shampoo is right for everyone.

Can DIY be done safely?

Despite the dangers of DIY, it can be done more safely. It’s important to avoid applying anything highly acidic directly to your skin. Dr. Yadav says that cucumbers, steeped and wrung-out tea bags, and ice cubes can be used to soothe irritated skin. Some DIY recipes are totally harmless, especially when they contain gentle ingredients and are not stored.

The most important principle when considering new skin and hair care practices is to know yourself and your own needs. If you’re having any skin-related issues, it’s best to consult a dermatologist before diving into natural remedies. While DIY is not inherently dangerous, there are many benefits to choosing products that have been created and tested in labs by experts.

In general, it’s wise stay away from internet-trending concoctions. Figuring out what is best for your skin and hair can be a long process, but taking the time to learn about your body’s needs and research the best methods and ingredients for you will be worth the effort.