If you’ve been finding more hair in your brush, your drain, or – let’s be honest – your vacuum cleaner, you’re not alone. Up to one in four adults experiences excessive shedding at some point, and medications are one of the most overlooked culprits.
Certain drugs and stress can push hair follicles into a “resting” phase where they go to sleep (called “telogen”). More specifically, the hair strands don’t even grow and they simply sit there until they fall out as is the natural process. This type of loss is called “telogen effluvium,” and it usually shows up 2–3 months after the triggering event. That’s why it’s so hard to connect the dots.
- Physical stress: Severe illness, high fever, surgery, giving birth, or sudden/significant weight loss.
- Emotional stress: A major life event like a death, or grief of some kind of loss, or a bad break-up
- Hormonal changes: Fluctuations from pregnancy, thyroid imbalances (there’s more on that below), or discontinuing certain medications.
- Nutritional deficiencies: A lack of protein or iron in the diet can do it, so many others – too much to list here.
But remember, I am a pharmacist so I’ve spent decades helping people decode hair loss as it pertains to their medication. And that is a HUGE unrecognized trigger for temporary hair loss. Most people just don’t think of it!
So no, it’s not always your hormones, your vegan diet, or your pickleball elbow! Sometimes…it’s your prescription bottle. That’s what I want to share with you today.
Let’s walk through the most common medication triggers, and then twoards the end of htis blog, I’ll talk about the one category that confuses everyone: Thyroid drugs. Do those drugs cause hair loss, or do they resolve it?
Medications Known to Cause Hair Loss
Below are 15 medications or (medication categories) that are most associated with shedding. Not every medicine in these groups will cause it, and not every person will react. Still I want you to know the big players if you have noticed some hair loss:
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Antibiotics & antifungals: They can alter gut flora and nutrient absorption, especially zinc and B vitamins—both required for healthy hair.
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Antidepressants & mood stabilizers: SSRIs, SNRIs, and some bipolar medications may trigger hair loss in sensitive folks.
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Anti-clotting medications: Medications like warfarin or heparin sometimes shift follicles prematurely into resting mode.
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Birth control pills & hormone therapy: Estrogen stabilizes hair growth. Changes in estrogen—up or down—can cause massive temporary shedding.
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Breast cancer drugs: Naturally, chemo is the most dramatic example, but even non-chemo cancer meds can influence hormonal pathways that affect hair.
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Cholesterol-lowering drugs (statins & others): Hair cells are metabolically active and sensitive to changes in cholesterol and CoQ10.
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Epilepsy medications: Some anticonvulsants alter folate and biotin pathways.
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High blood pressure medications: Especially beta-blockers, ACE inhibitors, and diuretics, which may disrupt circulation or nutrient homeostasis.
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Immunosuppressants: Drugs used for autoimmune disease may impact nutrient levels and hair cycling.
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NSAIDs (nonsteroidal anti-inflammatories): Chronic use can deplete folate and reduce blood flow to follicles.
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Parkinson’s medications.
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Retinoids (vitamin A–based acne drugs): Excess vitamin A shrinks sebaceous glands and speeds up shedding cycles.
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Steroids: Long-term corticosteroids suppress collagen production and thin the hair shaft.
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Weight-loss medications
Some reduce appetite or absorption, leading to nutrient deficiencies that impact hair.
15. Now for the Confusing One… Thyroid Medications!
You would think thyroid meds would stop hair loss. After all, low thyroid function can cause thinning. So why in the world are thyroid drugs on the list of medications that can cause shedding?
Let me clear this up simply:
**Thyroid medications do NOT cause hair loss when someone is on the right dose.
Hair loss happens when the dose is WRONG—either too high or too low.**
When you start or adjust thyroid medication, your body may temporarily shift hair follicles as it rebalances metabolism. This can cause shedding for 6–12 weeks, then it settles.
There are 3 major scenarios where thyroid meds seem to cause hair loss:
1. You’re under-treated (still hypothyroid)
If you’re taking levothyroxine but your body isn’t converting T4 → T3 well, you remain functionally hypothyroid.
And hypothyroidism causes shedding all by itself.
In this case, the medication isn’t the villain—it’s the lack of active T3.
2. You’re temporarily over-treated (slipping into hyperthyroid range)
Too much thyroid hormone speeds up hair cycling and pushes follicles into the shedding phase.
This can happen when:
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A dose is too high
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A pharmacy switches generic manufacturers
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You change brands
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You’re started on T3 or NDT without proper titration
Hyperthyroid states = fast hair growth cycle = fast shedding.
3. Your body reacts differently to certain brands or fillers
I hear this all the time in my inbox:
“My hair fell out after switching from Brand X to Brand Y.”
You are not imagining it.
Different brands and generics use different fillers, dyes, and binding agents. Some people are sensitive to:
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Crospovidone: An inactive ingredient used as a disintegrant to help the tablet break apart in the body. (Tirosint-SOL is free of this compound)
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Dyes (FD&C Blue, Red, Yellow)
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Lactose
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Gluten (These should all be gluten-free: Levoxyl, WP Thyroid, Nature-Thyroid, Tirosint, and a few generic brands of levothyroxine.)
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Acacia
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Talc
For those individuals, starting a new thyroid med can trigger inflammation → which affects nutrient absorption → which affects hair
So Should Thyroid Meds Be on the Hair-Loss List?
Yes, but ONLY for reasons of incorrect dosing, conversion problems that you have, or brand sensitivity issues, not because thyroid hormone itself harms hair. In fact, thyroid hormone (when dosed correctly) restores hair growth and beautiful skin, and faster nail growth.
The right medication at the right dose, actually helps hair regrow.
The wrong medication, dose, or formulation can cause temporary chaos.
How to Tell If Your Shedding Is Drug-Induced
Clues it could be your medication include:
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Hair loss started about one to three months after beginning a new drug
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Shedding worsened after switching brands or switching to a generic
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Your TSH is bouncing around
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You feel “off” after a med change
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You notice shedding along with anxiety, heart palpitations, coldness, or indescribable weakness or fatigue
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Your labs don’t match your symptoms (very common with thyroid issues because the reference ranges are skewed and have not been updated)
What You Can Do Next
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Review medications you started in the last 3 months – write them down, show a pharmacist, google or chat them – see what causes hair loss
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Ask your clinician about nutrient testing (ZINC, ferritin, B12, folate, selenium)
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Check thyroid labs: TSH, Free T3, Free T4, Reverse T3
Read this article next, Why Levothyroxine Isn’t Enough and 4 Ways Its Effect is Blocked -
If you suspect a thyroid med issue, ask to try a different brand or adjust the dose
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Be patient — temporary hair loss (medically called telogen effluvium ) almost always resolves when the trigger is removed
Your hair is a barometer of your metabolic health. When it’s falling, it’s trying to tell you something.
Summary
Hair loss is rarely about vanity—it’s about biology, balance, and biochemistry.
Medications can be lifesaving, but they can also nudge your follicles into a temporary resting phase.
With the thyroid specifically, the right medication restores hair.
The wrong medication—or wrong dose—can disrupt it.
If your hair started shedding around the same time you began a new drug, even a thyroid medication, do not ignore the timing. That’s often the biggest clue of all.
Suzy Cohen, has been a licensed pharmacist for over 30 years and believes the best approach to chronic illness is a combination of natural medicine and conventional. She founded her own dietary supplement company specializing in custom-formulas, some of which have patents. With a special focus on functional medicine, thyroid health and drug nutrient depletion, Suzy is the author of several related books including Thyroid Healthy, Drug Muggers, Diabetes Without Drugs, and a nationally syndicated column.
