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Common Causes of Sudden Hair Loss

Katelyn Hagerty

Medically reviewed by Katelyn Hagerty, FNP

Written by Our Editorial Team

Last updated 4/29/2021

Noticed extra hair loss recently? It’s normal to lose 50 to 100 hairs per day. However, a variety of issues may cause you to shed more hair than normal, resulting in stray hairs that can end up stuck in your hairbrush or left behind on top of your pillowcase.

Although most hair loss is gradual, some types of hair loss can occur suddenly, leaving you with noticeably thinner hair over the course of a few weeks or months.

Below, we’ve listed the most common causes of sudden hair loss, from forms of temporary hair shedding caused by things like stress, illness or medication use to permanent hair loss that can occur as a result of infections, hormones or your genetics. 

We’ve also explained what you can do to treat sudden hair loss, regrow lost hair and keep your hair looking and feeling its best in the future. 

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Sudden Hair Loss: The Basics

  • Sudden hair loss can occur for a variety of reasons, including illnesses that cause fever, severe stress and even certain medications.

  • If you’ve recently lost weight due to a crash diet or don’t get enough of certain essential nutrients, you may experience sudden hair shedding.

  • Although most types of sudden hair loss are reversible, it’s important to seek out expert help to get an accurate diagnosis and learn about the best treatment options.

  • Your healthcare provider may recommend several treatments for hair loss, including the hair regrowth medication minoxidil.

  • Our Complete Hair Growth Kit includes numerous science-backed products to help you regrow hair, decrease shedding and improve your hair’s strength.

Causes of Sudden Hair Loss

A variety of factors, from your diet to your genetics, your use of certain medications or your level of stress, may cause you to suddenly deal with hair loss. We’ve listed the most common causes of sudden hair loss below, along with the science behind why and how each one occurs.

Telogen Effluvium

Telogen effluvium is a common form of temporary hair loss. It often comes on suddenly and can cause abrupt, diffuse hair shedding that affects your entire scalp.

If you have telogen effluvium, you may notice a large number of hairs on your pillow, hairbrush or in your shower drain’s hair trap. You may also notice that your hair looks thinner and slightly less full than usual.

Telogen effluvium hair loss is temporary, but it’s important to treat the underlying cause to help your hair grow back to normal.

What Causes Telogen Effluvium?

Telogen effluvium is a reactive form of hair loss that’s caused by a triggering event. This could be a stressful experience, an illness or one of many other things. Common potential causes of telogen effluvium include:

  • Stress. You may notice this form of hair loss if you feel overly stressed, either due to a single stressful experience or chronic physiological stress that affects your wellbeing.

  • Illness. Some illnesses, particularly those that cause you to develop a fever, can cause this form of hair loss.

  • Injuries. Some people develop telogen effluvium hair loss after a physical trauma, such as an injury.

  • Infections. Infections, particularly severe infections, can also cause this form of hair loss to develop.

  • Surgery. You may experience telogen effluvium hair loss shortly after surgery, including during the recovery phase.

  • Medications. Certain medications, such as beta-blockers and anticoagulants, can cause this form of hair loss.

  • Thyroid issues. You may be more at risk of developing this form of hair loss if you have a thyroid problem, such as hyperthyroidism or hypothyroidism.

  • Crash dieting. Going on an extreme low calorie diet or losing a large amount of weight in a short period of time may cause telogen effluvium hair loss.

  • Nutritional deficiencies. Some nutritional deficiencies, such as iron deficiency anemia, can cause telogen effluvium hair loss.

Telogen effluvium hair loss generally becomes noticeable between one and six months after the triggering event. The shedding can last for a few weeks or as long as six months.

Most of the time, this form of hair loss will stop and your hair will grow back once the underlying cause is identified and treated. 

Anagen Effluvium

Anagen effluvium is a type of temporary hair loss that develops when your hairs are affected by a toxic substance or inflammation.

This type of hair loss usually occurs during treatment with certain medications, including certain drugs used during chemotherapy. Other medications, including those used to treat Parkinson’s disease, gout, rheumatoid arthritis and psoriasis, can also cause this form of hair loss.

Like with other forms of temporary hair loss, any hair you lose due to anagen effluvium will start to grow back once you stop using the causative medication.


It’s common to shed hair while you’re pregnant, as well as after you give birth. This type of hair loss is actually a form of telogen effluvium that’s likely caused by the abrupt hormonal changes that can occur while you’re pregnant.

According to the American Pregnancy Association, hair loss during pregnancy usually begins to diminish three to four months after you give birth.

During pregnancy, some medications that are commonly used to treat hair loss may not be safe for you to use, making it important that you talk to your healthcare provider if you’ve noticed any hair shedding. 

You can learn more about dealing with hair loss during pregnancy and after childbirth in our full guide to pregnancy and hair loss

Traction Alopecia

Traction alopecia is a type of hair loss that’s caused by hairstyles that put an excessive amount of pressure on the roots of your hair.

This type of hair loss can develop if you wear your hair in a tight ponytail, braids, dreadlocks or other hairstyles that place a pulling force on its roots. You may have a higher risk of developing this type of hair loss if you’re of African descent.

Some chemicals used in styling products and heat treatments might also contribute to this type of hair loss.

Although early-stage traction alopecia is usually treatable, over the long term, traction alopecia can damage your hair follicles and cause permanent hair loss.

We’ve talked more about traction alopecia in our blog, Can Ponytails Cause Hair Loss?

Alopecia Areata

Alopecia areata is a form of autoimmune hair loss that occurs in small, round patches. It affects about one in every 500 to 1,000 people in the United States and often develops over a period of several weeks.

Currently, there’s no cure for alopecia areata. However, medications such as corticosteroids can provide relief from symptoms and may help with this form of hair loss. 

Pattern Hair Loss

Pattern hair loss, or female pattern baldness, is a type of hair loss that’s caused by genetic and hormonal factors. 

Unlike many other types of hair loss, which cause sudden shedding, pattern hair loss generally causes you to lose hair in a specific pattern. For example, it’s common to notice hair loss close to your midline part -- the line along which your hair parts naturally. 

Most of the time, pattern hair loss occurs gradually instead of suddenly. However, some people may experience rapid hair loss that worsens over the course of several months. 

Although pattern baldness is much more common in men, approximately one third of all women will develop this form of hair loss at some point in their lives.

Like other types of hair loss, female pattern hair loss is treatable using medication. It’s important to start treating this form of hair loss as early as possible, as it can cause permanent damage to your hair follicles that may prevent hair from regrowing.

We’ve talked more about this type of hair loss, its symptoms and treatment options in our guide to female hair loss

Tinea Capitis (Scalp Ringworm)

Tinea capitis, or scalp ringworm, is a type of fungal infection that develops in your scalp hair. In addition to irritating your skin, it can make its way into your hair follicles and cause you to shed hair in certain areas of your scalp.

This type of infection is most common in children and teenagers, but it can potentially occur in people of all ages.

Although most hair loss from tinea capitis is temporary, when this infection becomes severe, it can cause an abscess called kerion that can cause permanent hair loss.

Because of this, it’s important to treat tinea capitis as quickly as possible. As a fungal infection, tinea capitis is treated using oral antifungal medications, either on their own or in combination with antifungal shampoos and other care products.

Hormonal Birth Control 

Although it’s uncommon, some birth control pills and other forms of hormonal birth control may cause you to shed hair if you’re genetically predisposed to hair loss.

According to the American Hair Loss Association, forms of birth control that have a high risk of causing hair loss include progestin implants, hormonal injections such as Depo-Provera®, skin patches and the NuvaRing® vaginal ring.

Certain birth control pills, particularly those with a high androgen index, may also contribute to hair loss.

To minimize your risk of hair loss, the American Hair Loss Association recommends using a pill with a low androgen index. If you use the pill, you can ask your healthcare provider for pills that have the lowest risk of stimulating androgen production and affecting your hair. 

Read about another potential cause of sudden hair loss in our article hair loss after a hysterectomy.

How to Treat Sudden Hair Loss

Sudden hair loss is treatable. In most cases, it’s possible to stop sudden hair loss and promote regrowth by treating the underlying cause of the hair loss, such as an illness, stress, nutritional deficiency or other health issue.

To stimulate hair regrowth, you may benefit from using hair growth medication. We’ve explained both of these options in more detail below. 

Treat the Underlying Cause of the Hair Loss

Most forms of sudden hair loss are caused by underlying health problems. For example, telogen effluvium often develops as a result of stress or illness, while tinea capitis develops due to scalp fungus. 

If you’re currently experiencing or have recently experienced sudden hair loss, it’s best to talk to your healthcare provider so that they can diagnose your specific type of hair loss. 

To treat the underlying cause of your hair loss, you may need to use medication. Make sure that you closely follow the instructions provided by your healthcare provider and use your medication for the entire treatment period.

If your hair loss is caused by a medication you already use, your healthcare provider may switch you to a different medication or adjust your dosage. Make sure not to make any changes to your use of medication without first talking to your healthcare provider.

Finally, if your hair loss is caused by a specific habit, such as wearing your hair in an overly tight ponytail, you may need to change your habits to prevent the hair loss from worsening. 

Use Hair Loss Medications and Care Products

While treating the underlying cause of hair loss can stop it from worsening, it may take several months for your hair to grow back.

To speed up the hair regrowth process, you may want to use a science-based medication such as minoxidil. 

Minoxidil is a topical medication that works by encouraging your hairs to enter into the anagen, or growth, phase of the hair growth cycle. It also helps to boost blood flow to your scalp, which may help to stimulate growth.

Using minoxidil is easy. It comes in liquid form and needs to be applied directly to the areas of your scalp with noticeable hair loss.

On average, it takes about eight weeks for minoxidil to start working, with the maximum effects usually visible after approximately four months.

We offer specially formulated minoxidil for women online, complete with convenient delivery to your home address.

In addition to minoxidil, hair care products such as shedding control shampoo, conditioner and biotin vitamins can help to support healthy hair growth. 

We offer these products individually as part of our selection of hair care products or together in our Complete Hair Kit

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In Conclusion

Sudden hair loss can develop for a variety of reasons, from nutritional deficiencies to problems such as injury, stress, infection or use of certain types of medication.

While products like minoxidil can help to stimulate hair regrowth, it’s important to treat the root cause of your hair loss before you focus on regrowing the hair you’ve recently shed. 

You can do this by talking to your primary healthcare provider, who will be able to diagnose the underlying issue and recommend a safe, appropriate form of treatment. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

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