If you're one of the many people who take prescription medications, you know that there's always a risk that you may experience unwanted or unpleasant side effects. Unfortunately, hair loss — aka alopecia — is a possible side effect of several prescription drugs. While hair loss can be distressing and cause a dip in your self-esteem, there is a bright side: It's most likely temporary.
Here's a look at some of the drugs that cause alopecia, how they affect the hair and what you can do if you notice hair loss after starting a new medication.
Types of Drug-Induced Alopecia
Before discussing what medications can cause hair loss, it's important to understand how they cause it.
Telogen Effluvium and Anagen Effluvium
The most common type of drug-induced hair loss is telogen effluvium or TE. When a patient takes a medication, it can have a toxic effect on the hair matrix. This interrupts hair growth, pushing it out of the growth (or anagen) phase and into the resting (or telogen) phase ahead of schedule. Then, two to four months later, all of this hair falls out together and results in excessive shedding.
However, this is not the only way drug-induced TE can happen. In rare instances, medications can cause club hair (hair in the resting phase that's still attached to the scalp) to fall out early. Some medications can also lengthen the growth phase, and if a patient stops taking that medication, TE can occur. Fortunately, this temporary hair loss often resolves on its own within six months, but it can persist if chronic.
The other type of drug-induced alopecia is called anagen effluvium (AE). During healthy hair growth, cells in the hair matrix divide quickly. Anagen effluvium occurs when a patient takes a drug that interferes with that process.
With AE, hair loss begins only seven to 10 days after taking the drug, and it becomes most apparent one to two months into treatment. While AE causes hair loss on the scalp, it also affects other body hair like eyebrows and eyelashes. This type of hair loss occurs with chemotherapy treatments, and while regrowth is often expected, it takes several months.
What Does Hair Loss Look Like?
When diagnosing patients, doctors classify hair loss as either diffuse or focal. Diffuse means it happens over a broad area. You might notice increased shedding or hair thinning across the entire scalp. TE is an example of diffuse hair loss. On the other hand, focal hair loss occurs in concentrated patches. While the cause of focal hair loss is usually diagnosed by the appearance of the patches, a scalp biopsy may be necessary to confirm the diagnosis.
Hair loss can also be classified as either non-scarring or scarring. Good news: Most cases are non-scarring. In fact, TE (the most common type of hair loss caused by medications) is a type of diffuse non-scarring alopecia. Scarring alopecia is rare and sometimes called cicatricial alopecia. Unfortunately, cicatricial alopecia destroys hair follicles and replaces them with scar tissue, preventing hair regrowth.
Medications That Can Cause Hair Loss
Now that you know how drugs can cause hair loss, here's a list of medications that have this potential side effect and how they affect hair growth.
These blood thinners are prescribed to prevent blood clots. "Warfarin (branded as Coumadin), a common blood thinner, definitely causes people to develop thinner hair with its use," says Dr. Robert Leonard of Hair Health Institute. Anticoagulants cause hair loss by inducing telogen effluvium. Therefore, excessive shedding would begin at least two months after starting the medication.
Antidepressants and Mood Stabilizers
Both antidepressants and mood stabilizers can cause alopecia due to TE. Lithium, a common treatment for bipolar disorder, has been shown to cause hair loss in up to 19% of patients who use it for an extended period of time. Valproic acid (or Valproate) is an anticonvulsant prescribed as a mood stabilizer. Depending on its dose and concentration, it has caused alopecia in up to 28% of patients.
Another anticonvulsant, carbamazepine, has the same effect but only in about 6% of cases. Rarely, tricyclic antidepressants lead to alopecia, and some patients have also reported hair loss with selective serotonin reuptake inhibitors or SSRIs.
Patients with human immunodeficiency virus — aka HIV — may take a combination of antiviral medications to slow the illness's progress. Some of these drugs include indinavir, ritonavir and lopinavir.
Indinavir can cause severe TE as well as patchy hair loss in up to 10% of patients. In fact, it can even change hair texture and shape or darken its color. And, when taken with ritonavir, hair loss may worsen because ritonavir increases the indinavir's concentration in the body. Lopinavir and ritonavir taken together have a similar outcome.
Oral contraception comes in two forms: the combination pill and the progestin-only pill. The estrogen in the combination pill prolongs the hair's growth phase. When a woman stops taking it, a large amount of hair can be pushed into the resting phase of the hair cycle, resulting in TE. Some women may also experience non-scarring focal hair loss three to five months after starting birth control pills.
Progestin-releasing implants and pills that contain certain types of progesterone, like norethindrone or levonorgestrel, can also lead to hair loss. However, in this case, the patient would experience androgenetic alopecia, also known as female pattern baldness. With implants, this side effect is most likely to occur at the beginning of treatment when progestin levels in the body are highest.
Busulphan is actually a chemotherapy drug. But patients may undergo busulphan conditioning before getting a bone marrow transplant. Researchers believe this conditioning can cause permanent damage to the hair follicle, preventing hair regrowth. Findings suggest up to 50% of patients who undergo this treatment can experience permanent alopecia.
Starting chemotherapy drugs can cause a different type of hair loss: anagen effluvium. According to research, about 65% of patients experience this side effect. Still, it is more likely to happen with specific medications and when taking a combination of chemotherapy drugs, as opposed to just one.
So why does hair loss occur during this cancer treatment? According to Dr. Leonard, "Because cells in hair follicles rapidly turn over, they are unintended targets of chemotherapy drugs, which treat rapidly growing cancer cells." Fortunately, this negative effect is often reversible, with new hair growth beginning one to three months after completing treatment.
Doctors have documented telogen effluvium in patients with Parkinson's disease who were treated with dopaminergic drugs, including bromocriptine, cabergoline, levodopa, pergolide, pramipexole and ropinirole. While the exact cause of this side effect remains unclear, TE has been reported more often in women than in men.
High Blood Pressure Medications
ACE inhibitors and beta-blockers, which are used to lower blood pressure, have been associated with temporary hair loss in a small percentage of patients. However, changing patients to a different medication has successfully resolved these instances of non-scarring TE.
Note: If you have lichen planopilaris, a type of scarring hair loss caused by the skin disease lichen planus, your doctor may choose to prescribe different anti-hypertensives, as ACE inhibitors and beta-blockers can both cause the condition to worsen.
Non-steroidal anti-inflammatory drugs rarely cause hair loss, and when they do, it often goes undiagnosed. Why? If a medication causes TE, hair doesn't start falling out until months later. So, by the time shedding starts, the patient doesn't always realize what's causing hair loss. NSAIDs that can cause TE include ibuprofen, indomethacin, naproxen and piroxicam.
Unlike most of the medical treatments on our list, radiation does not cause telogen effluvium. Radiotherapy, particularly when localized to the scalp to treat brain tumors, causes a condition called secondary cicatricial alopecia. Research shows radiation dosages above 700 Gray (Gy) destroy the hair follicle, preventing hair from regrowing. However, there's some good news, too. If the hair is in the telogen phase of growth during radiation treatment, the follicle can survive. Therefore, radiation treatment on the scalp may not result in complete baldness.
Vitamin A and medications derived from it can be used to treat skin conditions such as acne, psoriasis and cutaneous T-cell lymphoma. But high dosages of the vitamin or these medications can cause alopecia. This occurs most commonly when taking acitretin (to treat psoriasis) or isotretinoin (to treat severe acne and some cancers). With retinoids, TE is caused not by pushing growing hairs into the resting phase but by shortening the resting phase and causing hair to fall out early. So, the effects of TE can be seen sooner than three months after taking the medication.
Hypothyroidism (a deficiency of thyroid hormone) can cause alopecia. In a healthy hair cycle, 10%- 15% of hairs will be in the telogen phase at any given time. However, researchers found that patients with a low thyroid hormone have more hairs in the telogen phase. When treated with thyroid hormone replacement therapy, the hair returns to a normal balance. However, Dr. Leonard cautions that cells in the hair follicles are sensitive to hormone changes in the body. So, increasing thyroid hormone can initially cause shedding from telogen effluvium. Pharmacist Jessica Nouhavandi adds that while thyroid medications can cause hair loss, the side effect may also be due to inappropriate dosing of the medication.
What To Do if You Experience Drug-Induced Hair Loss
Not everyone will lose hair when taking these medications for health conditions. In most cases, it's a rare side effect. But if you suspect your prescription contributed to hair thinning or alopecia, you should seek medical advice ASAP. Talk to your pharmacist about the possible side effects of your medications. Also, consult with your doctor to discuss alternative treatments and rule out other possible causes of hair loss. Keep in mind that diagnosing drug-induced alopecia can be difficult, and the only way to confirm it may be to see if an improvement occurs after you stop taking the suspected drug." However, do not stop taking the medication without first consulting your doctor.
How To Help Hair Grow
Even if hair falls out due to medical treatment, it's often possible to grow it back. Here are some recommendations Dr. Nouhavandi shares to give your hair its best chance to grow and stay healthy.
Eat a Balanced Diet
Be sure to eat enough calories. Eating too few has been linked to hair loss. Plus, getting enough vitamins and minerals helps hair grow. Research shows that iron, omega-3s and antioxidants may all promote healthy growth. But too much of certain nutrients like vitamin A, vitamin E and selenium can actually cause hair to fall out.
Related: 16 Foods to Eat to Grow Your Hair
Smoking cigarettes constricts your blood vessels, including the ones that reach your hair follicles. When this happens, your hair cannot get the nutrients it needs from your bloodstream, interfering with the growth cycle.
Keep It Cool
Avoid heat styling, such as flat irons and curling irons, as much as possible. These tools cause unnecessary strain on your locks. And if you choose to pull your hair back, opt for friction-free hair ties that won't tug on your strands.
Get Regular Exercise
Yes, exercising regularly has been linked to greater growth. Keep your body moving and your strands growing with an appropriate workout routine.
Biotin, a B vitamin, helps with hair and nail growth. Taking a daily supplement like biotin gummies can prevent biotin deficiency and help you get other nutrients your hair needs for fuller, shinier locks.
Talk to Your Doctor
If your doctor determines you have drug-induced alopecia, remember there's still hope. Ask about your treatment options. In many cases, changing medications can stop hair loss. Then you can focus on your hair wellness routine to regrow your gorgeous locks and boost your confidence.
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