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  • Rajani Katta MD and Jaya Mahajan

Warning on the risks of hair loss supplements

Updated: May 7

As a dermatologist, I've been having lots of conversations about hair loss, especially in the last few years. With the Covid pandemic, quarantining, and all of the many, many other stressors of the last few years, I’m hearing more friends than ever before talk about hair loss.

It’s well known that certain physical factors, and even stress-related factors, can contribute to hair loss. So the many questions I get surrounding the topic of hair loss really aren't surprising.

I was surprised, however, that so many of those conversations started with this question: “What hair loss supplement should I be taking?“

Instead, my friends should be asking “What are your thoughts about hair loss supplements? Are they safe? Are there any risks?“

In a nutshell, although supplements have grown exponentially in popularity within the past decade, there's still so much that we don’t know about them. One thing we do know: sometimes they carry risks.

Hair loss supplements can be risky, and there is no such thing as FDA approval for supplements

The supplement industry overall is booming... and that’s not surprising. One reason is that there is very little barrier to entry. In fact, if you google “how do I make money with dietary supplements“, you’ll learn exactly how easy it is for a company to start selling these products.

When it comes to supplements, manufacturers do not have to provide any evidence of safety to the FDA before starting to sell their products. They don’t even have to prove that a supplement works.

The entire process is remarkably unregulated.

Manufacturers do have to abide by certain rules and regulations about labeling. But these are not the kind of regulations that you might think.

  • No pregnancy warning label is required, even for supplements that are known to cause birth defects.

  • No warning label about interactions with other medications or laboratory tests is required, even for supplements that the FDA has warned about.

  • Manufacturers do not need to prove that their supplement is of high quality.

  • They do not need to prove that their product is free from bacterial contamination.

  • They don't need to prove that their product is free from contamination with prescription medication ingredients.

  • Manufacturers are expected to comply with good manufacturing practices, but they don’t have to prove it, and the FDA is woefully understaffed when it comes to inspections of supplement factories.

Image of hair loss supplement pill and hair loss supplement bottle that lacks any warning labels
With supplements, manufacturers do not have to provide any evidence of safety to the FDA before starting to sell their products.

Supplements are considered foods, not medications, according to the government

There’s an interesting mismatch between the way manufacturers advertise supplements and the way that these products are regulated.

In 1994, the Dietary Supplement Health and Education Act was passed. This act legally recognized dietary supplements as foods, as opposed to drugs.

This means that while manufacturers are advertising their supplements as helpful for acne, hair loss, or memory loss, they don’t have to prove that their products are actually helpful for any of these conditions.

If the manufacturer doesn't have to prove effectiveness to the FDA or any regulatory body, then how do I know that a hair loss supplement will help hair loss?

In many cases, you simply don’t know

In most cases, consumers who buy a supplement are simply believing that what the manufacturer advertises is true.

In actuality, there’s sometimes very little science behind such advertisements.

  • In some cases, we simply don’t have any evidence that certain ingredients will help the average consumer.

  • In other cases, supplements may contain certain ingredients that have been studied and may be helpful in hair loss….but that also may be risky for certain individuals.

What do research studies show? Overall, they’ve found that some of the most commonly used ingredients in hair loss supplements have no actual proof regarding their effectiveness for consumers with normal levels of those ingredients.

Let me give you an example. Some children are born with a genetic defect that makes them unable to absorb selenium. Selenium is a mineral that’s found in certain foods. Some of these children develop severe hair loss, along with other problems. When you get their selenium levels back to normal, their hair loss improves.

However – and this is an important point – there’s no proof that taking selenium, if you already have normal levels, is going to improve your hair growth. In reality, the opposite is true: take too much selenium, and you can even develop hair loss.

A lot of hair loss supplement ingredients are like salt: too much can be worse than not enough

Most vitamins and minerals fall under the “Goldilocks principle“.

How much is the "right" amount of that vitamin? Not too little. Not too much. What you want is somewhere in the middle.

It’s just like salting your food. Sometimes taking too much can be even worse than not having enough.

Some hair loss supplements contain ingredients that can actually worsen hair loss, such as high doses of vitamin A, vitamin E, and selenium

One of the things that we found most surprising in the course of researching this article: that taking too much of certain supplements has been linked to a worsening of hair loss.

For example, ingredients like selenium, vitamin A, and vitamin E can increase hair loss issues. That’s why we found it so surprising that the best-selling hair loss supplement on Amazon contained both vitamin E and vitamin A, while the next one contained all three of these ingredients.

  • We’ve known for decades that taking too much vitamin A can cause skin, vision, and bone changes, along with hair loss.

  • Taking too much selenium can cause generalized hair loss, as well as blistering skin lesions, memory difficulties, and gastrointestinal symptoms.

Of course, those side effects are generally seen with high extra doses of these ingredients. However, unless a consumer is careful, they might pick a supplement that contains such high doses.

Ingredients like biotin can interfere with important laboratory tests

Biotin has been used in skin, hair, and nail supplements for a long time. Many people know of its use and it’s become almost a staple in the beauty world.

But it wasn't until 2017 that the FDA issued a really important warning: biotin can interfere with multiple laboratory tests. In one clinical trial, taking high doses of biotin interfered with 9 out of 23 laboratory tests.

It was found that biotin falsely decreased levels of a thyroid hormone, which means that healthy individuals could be misdiagnosed with thyroid problems. It also interfered with a test that is used to diagnose heart attacks, leading to at least one death.

Despite this important side effect of biotin, supplement bottles that contain high doses of biotin aren't required to list this important warning. It’s left to you, the consumer, to ensure that you’re properly informed.

Ingredients like vitamin A and saw palmetto are used in hair loss supplements and can cause birth defects

Nutrafol for Women is a popular hair loss supplement on Amazon, and it’s heavily marketed for hair loss.

It advertises one of its ingredients, saw palmetto, as important in treating hair loss. Saw palmetto has been studied extensively for other conditions because it inhibits a particular enzyme called 5-alpha reductase. This enzyme prevents the conversion of testosterone to dihydrotestosterone and therefore may help in hair loss.

However, you can start to imagine what might happen to a fetus when you start to interfere with hormone levels. In pregnant animals, administration of 5-alpha reductase inhibitors was associated with male offspring who had abnormal male genitals.

If this was an FDA-approved medication, this medication would be labeled pregnancy category X because of this risk of birth defects. (In other words, pregnant women should never take this medication.)

However, because these are supplements, there is no such required warning.

Vitamin A is also very concerning. In high doses, Vitamin A may cause birth defects, and the risk is especially high before the 7th week of pregnancy, at a time when some women may not be aware of their pregnancy. In one study, of pregnant women who averaged more than 10,000 IUs per day of vitamin A (in the form of retinoid compounds), approximately 1 in 57 had a child with a malformation that was likely due to the supplement.

We did a study looking at online acne supplements, and we found that some had similarly high doses of vitamin A that could cause such birth defects.

  • Despite this, supplement manufacturers are not required by the government to display any kind of pregnancy warning labels.

  • Some of the products in our review did have a label to "discuss with your physician if you are pregnant"... but the vast majority didn’t have any kind of warning label about this at all.

  • And none of the products that we looked at had a label that said “this product may cause birth defects.“

It’s buyer beware. In the end, it falls to the consumer to be really, really aware of these potential risks.

The ingredients in hair loss supplements have been linked to other risks...even a risk of cancer

When it comes to vitamins and minerals, more is not necessarily better. Instead, the right dose is the best dose.

(I'm going to repeat myself here with one of my favorite sayings about vitamins and minerals. It’s just like salting your food: too much can be even worse than not enough.)

In a review article we wrote about the risks of skin, hair, and nail supplements, we found that multiple research studies had linked high doses of certain vitamins and minerals to an increased risk of cancer.

  • Male smokers who took beta carotene supplements for a median interval of six years had an increased risk of lung cancer as compared to the group who did not take beta-carotene supplements

  • The long-term use of high-dose vitamin B6 and B12 supplements was associated with an increased lung cancer risk in men

  • Smokers who took high-dose vitamin B6 supplements over 10 years demonstrated a threefold increased risk of lung cancer

  • Researchers found that a 300 µg per day dose of selenium, taken daily for five years, increased all-cause mortality when assessed 10 years later. Some supplements that we've found contain selenium doses of 200 µg per day, and a single Brazil nut contains 90 µg. This means that somebody taking a supplement could easily exceed this dose.

Image of pills and supplements that may increase the risk of cancer
Multiple research studies have linked high doses of certain vitamins and minerals to an increased risk of cancer.

Supplements can be contaminated or adulterated, and it can be really hard to know this in advance

The current regulations ask manufacturers to utilize good manufacturing practices… but there’s no pre-market testing required to prove the quality of their product. The FDA has also reported that they are only able to inspect a small fraction of manufacturing facilities. At this point in time supplement manufacturers are basically on the honor system in regards to “good practices”.

Which brings up the question: have there been any problems reported with supplement quality?


Consumer Labs is an independent testing organization, and they have reported multiple quality issues with supplements. Their results have found that overall, about 1 in 5 supplements are considered poor quality.

What does poor quality mean? They’ve documented issues that range from poor quality ingredients to little or no ingredients even present in the product. Some of the products have even been contaminated.

Multiple reports have described contamination of supplements with bacteria, fungi, or heavy metals such as lead and mercury. Other products have been adulterated with prescription medications.

Some reports have described labeling errors and manufacturing errors that have led to serious side effects.

If product quality is such a concern, how can a consumer know whether or not a supplement is high quality?

Sometimes patients absolutely do need a supplement, such as elderly people with a vitamin B12 deficiency. In these cases, supplementation is necessary and life-saving.

If you need to take a supplement, then I always recommend looking for a label of certification. This indicates that a third-party independent lab has looked at this supplement and certified that it contains the ingredient listed on the label, at the dose indicated. It also certifies that the product is not contaminated or adulterated. (Just remember that certification of quality still doesn't tell you anything about the risks of birth defects or interference with testing or other risks.)

The NIH Office of Dietary Supplements recommends looking for certification by these organizations:

  • Consumer lab

  • NSF [National Sanitary Foundation]

  • USP [US Pharmacopeia]

  • UL [Underwriters Laboratory]

I myself have a subscription to Consumer Labs. They have multiple fantastic articles about the research that they do on supplement safety, quality, and effectiveness. These articles help consumers stay informed on supplements in general as well as highlight specific products.

One other thing to remember about dietary supplements: you don’t always know what’s in them. I would never take a supplement that contains a “proprietary ingredient blend"

Some of the hair loss supplements that we found contained “proprietary ingredient blends.“

Basically, this phrase means “it’s a secret!“

I don’t put any secret ingredients in my body, because I want to know exactly what I’m consuming.

We did a study about collagen powders, where we looked at lists of ingredients. We found that most of the products did not disclose where they were getting their collagen from.

This is a problem because of the risk of allergic reactions. For example, hydrolyzed fish collagen has been associated with anaphylaxis, a life-threatening type of allergic reaction… and unless the manufacturer discloses this on the label, you might have no idea that your collagen powder is sourced from seafood.

The bottom line: before you take a hair loss supplement, make sure you understand the risks and potential benefits of every ingredient that’s in there, along with the risks and benefits of that particular dose

Hair loss supplements are tricky because you have to understand so much about the regulations of supplements and then about the individual ingredients in a product.

Should you be taking a hair loss supplement? That's a good question to ask your physician.

  • Sometimes low levels of iron, zinc, and vitamin B12 can lead to hair loss, which is why your doctor may recommend a blood test.

  • Other times, you may not need a nutritional supplement. Instead, you may need to have a medical problem corrected, such as thyroid problems, which can lead to hair loss and lots of other medical issues.

  • In some cases, your hair loss may correct itself on its own. There’s a common cause of hair loss called telogen effluvium, in which your hair follicles go into hibernation. Given enough time, these cases of hair loss will often reverse, although it can take months.

If you do decide to go forward with a hair loss supplement, make sure you understand all of the potential risks. And at the very least, make sure that the product you are consuming has been tested and certified by an independent laboratory. And just remember: even if it is a high-quality product, it can still cause harmful side effects such as birth defects or interference with laboratory tests.

The bottom line: Supplements can be helpful, but they can also be harmful. It’s your job to educate yourself on the possible risks of supplements, since the FDA doesn’t do this for you. If you’re unsure, the best course of action is this: ask your doctor.


Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.

Jaya Mahajan is a student who is interested in health literacy and the risks of medical misinformation. She is one of the founders of Colors of Mind, a non-profit that partners with art therapists to provide assistance to children.

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