Your Hair Reveals Underlying Health Problems

Your hair has value behind aesthetics and confidence — in a way, your hair can be a bellwether for checking your health.

Your hair can signal surprising information about your health, doctors say — and the science behind it makes sense. Today’s example: hair changes, often in the form of hair thinning.

Ahead, skin doctors explain what different hair changes can tell you about your health and break down the steps to take after.

If your hair is shedding more, it could be a sign of dandruff — or it could signal thyroid problems.

“When there’s a problem with your thyroid, your hair is often one of the first things to show it,” said Dr. Hamdan Abdullah Hamed, a board-certified dermatologist and co-founder of PowerYourCurls.com.

Besides shedding more — and all over your head, especially after washing or when you wake up — you may notice your hair growing slower, he said, or feeling extra dry or rough.

“This shows up as thinning across the scalp, rather than bald patches,” added Dr. Vanita Rattan, a global skin doctor and founder of a skin care line. “Some people may also notice hair thinning around the outer edges of the eyebrows.”

Hamed explained what’s happening: Your thyroid affects your metabolism, which affects hair growth.

Depending on the specific hair “symptom,” you could have hypothyroidism or hyperthyroidism, he continued. If your hair isn’t growing as quickly, it could be because of hypothyroidism. Or, if your hair falls out faster than it grows back, you might have hyperthyroidism.

The first step is to have your thyroid function tested.

“Issues with thyroid hormones won’t go away on their own,” Hamed said. “If the levels are not right, getting medicine or hormone help from a doctor is really important.”

You might need more selenium, zinc and/or iodine, he added.

Rattan also suggested a lightweight strand-strengthening oil with key ingredients, such as amla oil, coconut oil, argan oil, jojoba oil, castor oil and sweet almond oil. She said this will “deeply nourish your hair without burdening it.”

Losing more hair than usual can also be an early sign of iron deficiency, especially in one population.

“Low iron levels are one of the most overlooked causes of hair shedding, particularly in women,” Rattan said. “You may notice hair coming out more during washing and brushing, or overall density can reduce without obvious patches of loss.”

Hamed added that hair may become especially thin at the top of your head or on the sides.

“You may also see that your hair looks dull, weak or doesn’t grow like it used to,” he continued.

What’s happening, according to Hamed, is that when the body is low on iron, it cuts back on nonessential processes, like hair growth. If you like a more scientific explanation, Rattan said low ferritin leads to impaired oxygen delivery to hair follicles, inhibiting growth.

Since hair loss doesn’t automatically mean your iron is low, it’s vital to ascertain that at the doctor’s office.

If you do have an iron deficiency, certain nutrients can help. Doctors recommended beef, lean meats, lentils, spinach, leafy greens, legumes and a daily collagen boost. Additionally, vitamin C helps the body absorb iron effectively.

Hormonal imbalances affect more than just your mood; they can also affect your hair in various places and ways. Levels of estrogen, testosterone, cortisol and thyroid hormones can all get out of whack, wreaking havoc on your hair.

“You may notice more hair falling out, thinning in specific areas or patches where hair is missing,” Hamed said.

“Alongside this, hormonal imbalances can also cause increased facial hair during life stages like menopause, or conditions such as PCOS,” Rattan added.

Your hair’s feel, not just its look, can change. “It might become dry, fragile or greasier than normal,” Hamed said.

Again, doctors agreed that checking your hormone levels is smart. Then, to manage that, consider managing stress, taking hormone treatment medication or insulin if needed, getting enough sleep and consuming more nutrients.

Stress is super common and hard-hitting, with effects including hair loss.

“You might see lots of hair coming out, especially when you brush it or shampoo,” Hamed said. “Some people notice their hair becomes thinner everywhere, while others have bald spots. Sometimes, hair just stops growing for a while.”

What’s happening here is similar to what’s happening with low iron levels: Your body prioritizes bodily functions that are more important than hair growth.

Further, stress specifically causes telogen effluvium, a pattern in which stress hormones prompt a large number of hairs to enter the shedding phase simultaneously, according to Rattan. “This is particularly common after a triggering event, physical stress on the body or periods of low mood,” she said.

Rattan and Hamed have good news: This form of hair loss is usually temporary, and reducing stress can help hair naturally regrow.

How to manage stress is the real question. While it’s easier said than done, there are doable options. Hamed and Rattan recommended getting better sleep, reducing caffeine intake, having boundaries at work, keeping your blood sugar steady, exercising, getting enough B vitamins, doing yoga or meditation, talking to a therapist, eating enough protein and giving your nervous system time to recover.

Does your hair feel rough, break easily or look lifeless? Has it been growing slowly or falling out more? Maybe you’re noticing a feeling of scalp tightness or flakes? Hamed said these signs indicate potential nutrient deficiencies.

“The most common deficiencies can include a lack of zinc, biotin, vitamin D, protein or omega-3s, which make strands weaker and more fragile,” Rattan added.

Think you’re getting enough of those nutrients but still having problems? You could have a gut health issue.

“When digestion or absorption is compromised, the body may struggle to take in key nutrients such as iron, B vitamins, zinc and amino acids, even if your diet appears balanced,” Rattan explained. “This can show up as increased shedding, slower growth and weaker strands over time.”

Necessary nutrients (in general and for hair growth) include protein, iron, zinc, biotin, omega-3 fatty acids, vitamin A, vitamin D and vitamin E. Supplements can help, Hamed said, but they need to be chosen carefully.

“The aim isn’t solely to promote hair growth,” he added. “It’s about giving your body what it needs so it feels secure enough to grow hair.”

Additionally, Rattan encouraged getting rid of dead skin cells once a week with a fragrance-free scalp exfoliator. Food-wise, she suggested foods rich in protein, nuts, seeds, fatty fish, eggs and greens to promote stronger, healthier hair from within.

Your hair can do a lot of things when you’re dehydrated: get tangly, feel like dry straw, produce split ends, experience static electricity, lose shine or cause your scalp to feel tight, itchy or start peeling.

“When you’re dehydrated, blood doesn’t flow as well to your hair roots, which results in fewer nutrients and less moisture for your hair,” Hamed said. “If this keeps happening, your hair can become weak, look dull and fall out more often.”

Note that the effects of dehydration on hair may not be direct.

“While dehydration doesn’t necessarily cause hair loss at the root, it can weaken the hair shaft, which impairs scalp health,” Rattan explained. “This can make hair appear more dull, frizzy and prone to breakage.”

Drinking more water is the obvious answer. Rattan recommended two liters a day, plus more if it’s hot outside, you exercise or you drink extra caffeine.

“If you struggle with this, incorporate water-rich foods like cucumber, watermelon and celery into your diet, as well as opting for herbal teas instead of coffee,” she continued.

While getting enough water is key, it’s not the only necessary step.

“It’s not enough to simply chug a gallon and expect everything to be fine,” Hamed said. “Adding electrolytes, such as sodium, potassium and magnesium, helps your body actually make use of the water you consume.”

From an external standpoint, Hamed recommended hydrating masks or scalp oils — especially if you live in a dry area or use heat on your hair — and Rattan said you can rehydrate strands with a cuticle repair conditioner.

While health conditions and assessments are more “hairy” than just checking your strands, a look in the mirror can be a simple first step. It isn’t a crystal ball with all the answers — and shouldn’t be used that way — and it may have more insight than you’d think.