
Hair loss or changes to hair can cause severe emotional distress. Hair plays a vital role in appearance and self-esteem, so suddenly losing hair can be devastating. If you have unexplained hair changes, your first instinct might be to ask for advice from your hairstylist. But you may need a doctor to get to the bottom of the issue.
Many health conditions can lead to hair loss. It's often an expected side effect if you're in treatment for cancer. Other conditions are harder to diagnose, and your doctor may need to do many tests to understand the relationship between your hair and your health.
Health issues that cause hair loss
Hair change or hair loss are side effects of some conditions. If you have unexplained hair changes, your doctor may test you for underlying causes, including:
- Lupus
- Psoriasis flare-ups on the scalp
- Thyroid disorders
- Malnutrition or rapid weight loss
- Syphilis
- Sex-hormone imbalances such as polycystic ovarian syndrome (PCOS)
If you have any of those conditions, your doctor will recommend treatment for the underlying health problem. Once you have other symptoms under control, your hair may start to return to normal. It can take many months for the hair to return to typical volume and texture after an illness.
Medication effects
Many medications can affect your hair other than chemotherapy drugs. You might notice thinning hair or hair changes if you take lithium to manage mood disorders. Beta-blockers for high blood pressure and blood thinners like warfarin or heparin can both cause hair loss. Medications to control the symptoms of Parkinson's disease can also lead to hair changes.
Hair usually starts to grow back several months after finishing cancer treatment, though your new growth may be different than it was before. Hair may be curlier or straighter, it might change texture, and the color could be different.
If a medicine you take has caused your hair loss, you may be able to get your hair back to normal if you stop the medication. Speak with your doctor before stopping any prescription. You could have serious health problems if you abruptly stop a medication.
Scalp infections
Injury and infection of the skin of your scalp can affect hair. Fungal infections like ringworm or tinea capitis damage the scalp and weaken the hair shafts. Hair can break off near the scalp or fall out at the roots. Tinea capitis can cause dry, flaky patches on the scalp. If you have ringworm, you might notice dry patches with red rings around them.
Once you treat the underlying infection, the skin on your head will start to heal. Hair will usually begin growing back once the skin is healthy again. In some cases, scarring can affect whether hair grows back normally.

SLIDESHOW
Your Hair and Scalp Can Say a Lot About Your Health See SlideshowAlopecia
Alopecia is an autoimmune disease that causes hair loss. If you lose hair in small, round patches, it's known as alopecia areata. If you lose all the hair on your head, it's called alopecia totalis. It isn't clear what causes alopecia. Alopecia can also cause you to lose hair from your eyebrows, eyelashes, or other body hair. People with other autoimmune diseases are at higher risk of developing it.
Hair can grow back after alopecia, but it doesn't always return. Some treatments such as steroid injections or drugs for autoimmune conditions can stimulate new hair growth.
Telogen effluvium
This type of hair loss happens several months after a serious physical stressor, such as a major illness, surgery, or an infection. This reaction is very common after childbirth. Covid-19 infections can also lead to telogen effluvium.
In these cases, hair loss happens because the physical stress of illness or the hormone changes from pregnancy change the hair's usual cycle of growth, resting, and shedding phases. Humans typically shed 50-100 strands of hair per day. In a telogen effluvium episode, the shedding phase accelerates, and more hair than usual falls out.
The hair typically begins to grow back right after the shedding phase ends. You may notice a lot of short hairs emerging between longer hairs. This is a normal part of the regrowth process.
Male or female pattern baldness
Age and heredity can lead to thinning hair. Male pattern baldness usually causes a receding hairline or a bald patch on the top of the head. Female pattern baldness leads to thinning on the top of the scalp.
If you notice thinning hair due to age, you can treat it with medications to slow hair loss. Some medicines will help regrow hair, or you can have surgery to implant new follicles on your scalp.
Harvard Health Publishing: "Hair Loss."
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