Hair and supplements
Hair Loss From Vitamins: What to Check First
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed October 20265 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
QUICK ANSWER
It can, but usually only at high doses. Too much vitamin A or selenium is linked with hair shedding. Add up every product you take against the NHS limits first. Then rule out the more common causes with a blood test: thyroid function, iron stores, vitamin D and B12.
Not sure which markers you need? Build your test →You started a multivitamin to feel better. Now there is more hair in the brush than there used to be, and the obvious suspect is the new bottle.
It might be. But it is often not, and stopping blindly can hide the real cause.
1. Can a vitamin really make your hair fall out?
Yes, though the dose is the whole story.
“Excessive intake of vitamin A and selenium, for example, can lead to increased hair loss.”
A 2019 review in Dermatology and Therapy says the same of vitamin A, and lists hair loss and brittle nails among the signs of too much selenium.
A single standard multivitamin rarely gets you there. The trouble usually starts when several products overlap.
2. What should you check on the label?
Add up each nutrient across everything you take, then compare the total with the NHS line.
- Vitamin A. The NHS says food and supplements together should not go over 1.5mg (1,500 micrograms) a day.
- Selenium. The NHS says 350 micrograms or less a day from supplements is unlikely to cause harm.
- Biotin. Not a hair loss cause, but it can skew thyroid blood results.
Vitamin A hides under other names. Look for retinol, retinyl palmitate and fish liver oil. A multivitamin, a hair gummy and a spoon of cod liver oil can stack up fast.
Our guide to too much selenium covers the other early signs, like garlic breath and a metallic taste.
3. Is it the supplement or something earlier?
Timing is the best clue you have.
The most common kind of sudden shedding is called telogen effluvium. That is when lots of hairs switch into their resting phase at once, then fall out together. The British Association of Dermatologists says it tends to show around three months after whatever set it off.
So ask why you started the multivitamin. Many people start one after an illness, a stressful spell, a diet or months of feeling tired. Those are classic triggers in their own right, and the NHS lists illness, stress, weight loss and iron deficiency as causes.
If the shedding began a few weeks after the first tablet, the reason you started may matter more than the tablet. Our telogen effluvium guide explains that three-month rule in full.
4. Which blood markers are worth checking?
The ones that point to the usual causes of shedding.
- TSH. The signal your brain sends to the thyroid, which rises when the thyroid is running slow.
- Free T4. The main thyroid hormone itself, read alongside TSH.
- Ferritin. The protein that holds iron in reserve, so it shows how much iron you have banked.
- Vitamin D and vitamin B12. Two nutrients that run low in a lot of UK adults.
One practical step first. If anything you take contains biotin, pause it for at least 48 to 72 hours before a thyroid test. Our biotin guide explains why it can throw the result.
Our hair loss blood test guide covers the wider set, and the full blood count guide covers the anaemia side.
5. Should you stop the multivitamin?
If your totals are over the NHS lines, cutting back makes sense.
If they are not, stopping may change nothing. You will also lose the chance to see what was actually low or off. Test first, then decide with the numbers in front of you.
Never stop a medicine you were prescribed without speaking to the person who prescribed it. And see a GP rather than waiting if hair falls out in patches, your scalp is sore or scaly, or shedding runs past six months.
Whether you need a multivitamin at all is a fair question too. Our multivitamin guide weighs it up.
6. Which test reports these markers?
Helvy’s General Energy & Wellness panel (£149) reports TSH, free T4, vitamin D and B12. Our Vitamins & Minerals panel (£159) reports ferritin with a full iron workup, plus vitamin D, B12, folate and magnesium.
One honest limit. No Helvy panel measures vitamin A, selenium or zinc. If you think you have overdone one of those, a GP can arrange that test.
Not sure which fits? The build-my-test tool walks you through it, and the energy and fatigue hub collects our thyroid and iron guides.
READY TO TEST?
Check the common causes before you blame the bottle
Helvy’s home blood tests report thyroid, vitamin and iron markers together, so you can see what is low before you change anything. Samples are processed by UKAS-accredited UK labs.
Frequently asked questions
Can a multivitamin cause hair loss?
At normal doses, rarely. Harvard Health says too much vitamin A or selenium can lead to increased hair loss, so the risk comes from high doses or from stacking several products that contain the same nutrient.
How much vitamin A is too much?
The NHS says your daily intake from food and supplements together should not go over 1.5mg (1,500 micrograms). Adults need around 600 to 700 micrograms a day, and most people get that from food.
Will my hair grow back if I stop the supplement?
If an excess was the cause, shedding usually settles once the excess is gone, but hair grows slowly and regrowth takes months. The NHS says most hair loss is temporary and grows back.
Should I stop taking biotin before a blood test?
Yes, if the test includes thyroid markers. Biotin can skew some lab results. The usual advice is to pause it for at least 48 to 72 hours first, and to check your multivitamin label for it too.
Can a blood test show if my supplement caused my hair loss?
Not directly. Helvy panels do not measure vitamin A or selenium. What a test can do is check the common non-supplement causes, such as thyroid function, iron stores, vitamin D and B12.
Related panels
Keep reading