What Is Hair Cycling and How Does DHT Disrupt It?

What Is Hair Cycling?

Hair cycling is the repeating life cycle of every hair follicle on your body. Each follicle moves through three main phases, and at any given moment different follicles are in different phases. That's why you don't shed all your hair at once. On a healthy scalp, roughly 80 to 90 percent of follicles are actively growing, while the rest are transitioning or resting. The whole cycle can last anywhere from two to six years depending on the person and the body area.

• Anagen (growth phase): The follicle is actively producing a hair shaft. This phase lasts two to six years on the scalp and determines how long your hair can grow.
• Catagen (transition phase): A short phase of about two to three weeks where the follicle shrinks and detaches from the blood supply.
• Telogen (rest phase): The follicle rests for around three months. The old hair is pushed out and a new one begins to form, restarting the cycle.
• Exogen (shedding): The moment the old hair actually falls out, often triggered by washing or brushing.

When this cycle runs normally, you lose around 50 to 100 hairs a day and replace them at the same rate. The problem starts when something shortens the growth phase or lengthens the resting phase. That's exactly what DHT does in people who are genetically sensitive to it.

How DHT Disrupts the Hair Cycle

DHT (dihydrotestosterone) is a hormone made from testosterone by an enzyme called 5-alpha reductase. It's not inherently bad. DHT plays a role in male development, but in certain people, hair follicles in the front and top of the scalp are genetically programmed to be sensitive to it. When DHT binds to receptors in those follicles, it gradually miniaturizes them. The growth phase gets shorter with each cycle, the hair shaft becomes thinner and shorter, and eventually the follicle stops producing visible hair altogether. This process is called androgenetic alopecia, or pattern hair loss.

Causes and Risk Factors of DHT-Related Hair Loss

The main driver is genetics. If you inherited follicles that are sensitive to DHT, you're likely to experience pattern hair loss at some point. But genetics isn't the only factor. Hormone levels, age, and even lifestyle can influence how quickly the process moves.

• Genetics: A family history of male or female pattern baldness is the strongest predictor.
• Hormones: Normal testosterone levels are enough to produce DHT. You don't need high testosterone for DHT-related loss to occur.
• Age: The likelihood and severity increase with age, though it can start in your late teens or early twenties.
• Medical conditions: Polycystic ovary syndrome (PCOS) and other hormonal imbalances can accelerate DHT activity in women.
• Medications: Some steroids and hormone therapies can worsen the condition.
• Stress and nutrition: Severe stress, crash diets, and deficiencies in iron, zinc, or vitamin D can compound the problem, though they don't cause DHT sensitivity itself.

Symptoms and Stages of DHT-Driven Hair Loss

DHT-related hair loss follows a predictable pattern in most people. It usually starts with thinning at the temples or crown in men, and a widening part or diffuse thinning over the top of the scalp in women. Unlike telogen effluvium, which causes sudden shedding all over, DHT-driven loss is gradual and localized. You might notice more hair in your brush, a receding hairline, or a scalp that's more visible under bright light. The earlier you catch it, the more options you have.

How Is DHT-Related Hair Loss Diagnosed?

Diagnosis is usually straightforward. A doctor or dermatologist will ask about your family history, when you first noticed thinning, and whether you've had any recent illnesses, stress, or medication changes. They'll examine your scalp, often using a magnifying tool called a dermatoscope to look at hair shaft thickness and follicle density. In some cases, they may order blood tests to rule out thyroid issues, iron deficiency, or hormonal imbalances that can mimic DHT-related loss.

• Medical history: Family pattern, timeline of loss, and any triggers.
• Scalp examination: Visual inspection and dermatoscopy to assess miniaturization.
• Hair pull test: Gentle pulling to see how many hairs come out and in what phase.
• Blood tests: Ferritin, thyroid function, vitamin D, and hormone panels if needed.
• Biopsy: Rarely needed, but can confirm the diagnosis if other conditions are suspected.

Treatment Options for DHT-Disrupted Hair Cycling

Treatment aims to slow or stop DHT from shrinking follicles, and in some cases, encourage regrowth. The earlier you start, the better the results. No treatment works for everyone, and results take months to show. It's also important to know that most treatments need to be continued to maintain benefits.

• Finasteride: An oral prescription drug that blocks the enzyme that converts testosterone to DHT. It's approved for male pattern hair loss and can slow loss and promote some regrowth.
• Minoxidil: A topical solution or foam that prolongs the growth phase and widens blood vessels in the scalp. Available over the counter for men and women.
• PRP (platelet-rich plasma): Injections of your own concentrated platelets into the scalp to stimulate follicle activity. Often used alongside other treatments.
• Ketoconazole shampoo: An antifungal that may have mild anti-androgen effects on the scalp. Sometimes recommended as an adjunct.
• Laser therapy: Low-level laser devices may improve hair density in some users, though evidence is mixed.
• Hormonal therapy: For women, anti-androgens like spironolactone may be prescribed off-label.

Is a Hair Transplant Suitable for DHT-Related Hair Loss?

A hair transplant can be an excellent option for DHT-related hair loss, but it's not a cure. The procedure moves DHT-resistant follicles from the back and sides of the scalp to thinning or bald areas. Those transplanted hairs usually keep their resistance to DHT, so they tend to survive long-term. However, the native hair around them may continue to thin if you don't use medication. That's why a transplant is often part of a broader plan that includes finasteride, minoxidil, or PRP.

• Good candidates: People with stable hair loss, sufficient donor hair, and realistic expectations.
• Less ideal candidates: Those with active, rapidly progressing loss or insufficient donor supply.
• Timing: Many surgeons recommend waiting until hair loss has stabilized, often after a year on medication.
• Procedure types: FUE (follicular unit extraction) and FUT (follicular unit transplantation) are the two main methods.
• Aftercare: You'll need to protect the grafts for the first week and avoid strenuous activity for a couple of weeks.

FAQ: Hair Cycling and DHT

Understanding hair cycling and DHT gives you a clearer picture of why hair loss happens and what you can do about it. If you're noticing changes in your hair, a diagnosis is the first step. From there, you and your doctor can decide whether medication, PRP, a hair transplant, or a combination is right for you.