Hair thinning is a mysterious beast; all too often, there isn’t an easy answer to why it’s happening. And when your hair thins in your twenties or early thirties, it can be even more distressing. From underlying health conditions to medications and environmental stressors, the causes are often complex. To shed light on the issue, we tapped board-certified dermatologists and plastic surgeons to break down some of the most common reasons behind hair thinning—and what you can do about it.
Featured Experts
- Janine Hopkins, MD is a board-certified dermatologist with practices in Southlake, TX and Monroe, LA
- Daniel Crane, MD is a board-certified plastic surgeon based in Delray Beach, FL
- Tina Alster, MD is a board-certified plastic surgeon based in Washington D.C.
- Kally Papantoniou, MD is a board-certified dermatologist based in Melville, FL
- Doris Day, MD is a board-certified dermatologist based in New York
Getting to the Root of the Problem
“Hair loss is extremely complicated,” explains Monroe, LA dermatologist Janine Hopkins. “Just the consultation can take over half an hour because we have to sift through a patient’s lifestyle, habits, medications and potential underlying health issues. It depends on their gender, age, hormones, stress level and hair habits.” Another major factor? Genetics. “Genetics play a large role,” adds Washington D.C. dermatologist Tina Alster, MD. For instance, “If a person’s mother or father experienced hair loss, then that person has a much higher risk of developing the same.”
When your hair starts thinning in your twenties, genetics may still play a role. But if your parents didn’t lose their hair young, finding the root cause can be a challenge. “Hair thinning can sometimes feel like a mystery, especially when it’s caused by less obvious factors,” says Melville, NY dermatologist Kally Papantoniou. But one thing that’s true across the board is that when you notice your hair is thinning or shedding, it’s important to be proactive and consult an expert. In some cases, a doctor may prescribe “oral or topical medications, or a combination of both,” says Delray Beach, FL plastic surgeon Daniel Crane, MD.
For many patients, hair thinning—a gradual decrease in hair density over time—or loss—where larger patches of hair fall out at once—can result from a mix of contributing factors. “The majority of the hair loss cases I see are multifactorial,” Dr. Hopkins explains. “Like on a multiple choice test, we find that ‘all of the above’ is often the right answer.” Below, explore some of the most common causes of hair thinning and hair loss that could be affecting you.
Diet and Hair Thinning
Diet-related hair thinning can cause a gradual decrease in hair density, which is often unnoticeable at first.
“Nutritional deficiencies, such as low levels of vitamin D, iron or biotin, can impact hair growth by disrupting the natural hair cycle,” Dr. Papantoniou explains. “Eating a well-balanced diet rich in leafy greens, nuts and fatty acids can often help address this.”
“People rarely eat enough protein,” Dr. Hopkins adds. “And if someone is not getting enough nutrients in one area, it’s possible they’re also going to be low in things like iron and vitamin D.”
Medication and Hair Thinning
“Certain medications, such as Ozempic, blood pressure medications or antidepressants, may also contribute to hair thinning by affecting the hair growth cycle,” explains Dr. Papantoniou. “If you suspect this might be a factor, discussing alternatives or adjustments with your healthcare provider could help.”
For those taking weight loss medications, Dr. Hopkins suggests working with a nutritionist to minimize potential side effects.
Scalp Health and Hair Thinning
For your hair to grow strong and healthy, the scalp has to be in ideal condition. “Your scalp health also plays a critical role in hair thinning,” Dr. Papantoniou says. “Scalp buildup, whether from styling products or untreated conditions like dandruff, can clog follicles and create an unhealthy environment for hair growth.”
Trauma and Stress Hair Loss
Stress-related shedding often appears more like hair loss rather than thinning and tends to be more sudden.
“Any major physiologic change, like rapid weight loss, can cause a stress shedding, called Telogen effluvium,” says New York dermatologist Doris Day, MD. “This causes hair follicles to enter the resting phase prematurely and fall out.”
But this stress-related hair loss isn’t just caused by rapid weight loss. “It can also be the result of physical illness, general anesthesia from surgery and even childbirth,” Dr. Hopkins says. “Essentially anything that interrupts the supply chain in your body that allows for hair growth, the entire factory may shut down. Without the nutrients to produce, you’ll get a sub-optimal product, where hair gets weaker and thinner, or doesn’t grow at all.”
