What Causes Hair Loss?

Genetic Pattern Hair Loss (Androgenetic Alopecia)

By far the most common cause of hair loss in both men and women is androgenetic alopecia - genetic pattern hair loss. It's driven largely by DHT (dihydrotestosterone), a hormone that gradually shrinks genetically sensitive hair follicles until they produce thinner, shorter hairs and eventually stop. In men this typically shows as a receding hairline and crown thinning; in women, as diffuse thinning and a widening part.

This matters enormously for supplement expectations: an antioxidant formula doesn't meaningfully affect DHT or the genetic process. That's why the treatments proven to help pattern hair loss - like minoxidil and finasteride - work through entirely different mechanisms, and why a supplement can't substitute for them.

Telogen Effluvium: Stress and Shock Shedding

Telogen effluvium is a common, usually temporary shedding that happens when a stressor pushes many hairs into the resting/shedding phase at once. Triggers include major physical or emotional stress, illness or high fever, surgery, childbirth, rapid weight loss, and starting or stopping certain medications. The shedding often appears two to three months after the trigger and typically recovers once the cause resolves.

Nutrient Deficiencies

Deficiencies can contribute to hair problems. Iron deficiency is a well-recognized cause of shedding, especially in menstruating women. Low zinc, vitamin D, or protein can also affect hair. Where a deficiency exists, correcting it (ideally guided by blood tests) can help. But the key nuance is that supplements mainly help when you're low - and overdoing certain nutrients backfires: excess selenium, vitamin E and vitamin A are documented causes of hair loss.

Hormonal and Thyroid Changes

Hormones strongly influence hair. Thyroid disorders (both under- and overactive) commonly cause hair thinning. Hormonal shifts around pregnancy, postpartum, menopause and conditions like PCOS can all affect hair growth. These causes are diagnosable and often treatable - which is exactly why a doctor's assessment beats guessing with supplements.

Autoimmune and Medical Causes

Alopecia areata is an autoimmune condition causing patchy hair loss, sometimes rapidly. Scalp conditions (fungal infections, severe dermatitis, scarring alopecias) and some systemic illnesses also cause hair loss. These need medical diagnosis and specific treatment - a supplement is not an appropriate response to sudden or patchy loss.

Hair Practices and Lifestyle

How you treat your hair matters. Tight hairstyles (traction alopecia), excessive heat, harsh chemical treatments and rough handling cause mechanical damage and breakage over time. Smoking is associated with worse hair health, likely via oxidative stress and reduced circulation. These are modifiable - gentler habits help.

The Bottom Line on Hair Loss Causes

Hair loss isn't one condition with one cause - it's a symptom with many possible drivers, from genetics and hormones to stress, nutrition and medical conditions. That's why the first step isn't buying a supplement; it's identifying your cause, ideally with a doctor. Once you know what's driving your hair loss, you can choose an approach that targets it - and understand where something like Restolin might (modestly) fit, and where it won't help at all.

Male vs Female Pattern Hair Loss

Although genetic pattern hair loss affects both sexes, it often looks different. Male pattern hair loss typically follows a recognisable route: a receding hairline at the temples, thinning at the crown, and over time these areas can merge. Female pattern hair loss more often shows as diffuse thinning across the top of the scalp with a widening part, while the frontal hairline is usually preserved. Recognising your pattern helps distinguish genetic loss (gradual, patterned) from other causes (sudden, diffuse or patchy), which points toward the right response.

This distinction also shapes realistic expectations. Patterned, gradual loss is the type least likely to respond to a supplement, because it's driven by hormones and genetics rather than nutrition or oxidative stress. Diffuse shedding that came on suddenly is more likely to have a reversible trigger - stress, illness, a nutrient gap - where supportive measures, and addressing the trigger, can help.

Medications and Medical Treatments That Cause Hair Loss

A frequently overlooked cause of hair loss is medication. A wide range of drugs can trigger shedding, including some used for blood pressure, mood, acne (high-dose vitamin A derivatives), blood thinning, and hormonal conditions, among others. Chemotherapy is the most dramatic example, but many everyday medications can contribute to telogen effluvium in susceptible people. If your shedding started after a new prescription, that timing is worth discussing with your doctor - never stop a prescribed medication on your own, but a review may identify a culprit or an alternative.

This is another reason a supplement is the wrong first move for new or unexplained hair loss. No amount of antioxidant support will counteract a drug-induced shedding pattern; identifying and, where appropriate, adjusting the trigger is what helps. It's a clear illustration of why diagnosing the cause always comes before choosing a response.

Putting It Together: A Sensible First Response

With so many possible causes, the most useful thing you can do isn't to pick a product - it's to observe and investigate. Note when the shedding started, whether it's diffuse or patchy, gradual or sudden, and whether it lines up with a life event: a stressful period, an illness, a new medication, a diet change, childbirth, or a family history of thinning. These details are exactly what help a doctor narrow the cause quickly.

From there, a simple set of blood tests can check the common, treatable contributors - iron, thyroid, vitamin D and more. If those are clear and the pattern is genetic, you can make an informed choice about evidence-based treatments. If a trigger like stress or a nutrient gap is found, addressing it directly is what helps. In every scenario, a supplement like Restolin is at most a minor supporting player - never the diagnostic step, and never a substitute for understanding what is driving your hair loss. Approached this way, you spend your effort and money where they genuinely count, and you avoid the common trap of treating a symptom for months while the real cause goes unaddressed.