Hair Loss from Radiotherapy, Hormones, and Medications: A Practical Guide

Does Radiotherapy Cause Hair Loss?#

Yes, radiotherapy can cause hair loss, but only in the specific area of the body receiving radiation. This is one of the most important distinctions to understand if you or someone you care for is about to start treatment. Unlike chemotherapy, which circulates through the bloodstream and can cause widespread shedding across the whole body, radiotherapy is targeted. If the treatment field doesn't include your scalp, you won't lose the hair on your head.

That said, hair follicles are among the body's most rapidly dividing cells, which makes them particularly vulnerable to ionising radiation. When the treatment field overlaps with a hair-bearing area, the follicles within that zone can be disrupted, sometimes temporarily, sometimes permanently.

How Radiotherapy Affects Hair Follicles#

Radiotherapy works by damaging DNA in rapidly dividing cells, preventing them from replicating. Cancer cells are the target, but follicle cells divide quickly too, making them collateral damage in the process.

The degree of hair loss depends on several factors:

• The total radiation dose delivered to the area
• The fractionation schedule (whether the dose is given in one go or spread over multiple sessions)
• The size of the treatment field
• Individual sensitivity, which varies considerably between patients
• Whether chemotherapy is being given at the same time

For most scalp-directed treatments, noticeable hair loss typically begins 2 to 3 weeks after radiotherapy starts. At lower doses (under 25 Gy), regrowth usually begins within 2 to 3 months after treatment ends. At higher doses, the damage to follicle stem cells can be permanent.

Is the Hair Loss Permanent?#

This is the question most patients want answered straight away, and the honest answer is: it depends on the dose. Lower-dose radiotherapy generally causes temporary loss. Higher doses, particularly those used for aggressive tumours, can permanently destroy follicle stem cells in the treated area. Your clinical team will be able to give you a clearer picture based on your specific treatment plan.

In some cases, hair that does return may be finer, a slightly different texture, or slower growing than before. This is normal and doesn't mean regrowth has failed.

How Is This Different from Chemotherapy Hair Loss?#

Chemotherapy drugs enter the bloodstream and affect rapidly dividing cells throughout the entire body, which is why hair loss from chemo tends to be diffuse and widespread, including eyebrows, eyelashes, and body hair. Radiotherapy is localised. Hair loss only occurs within the treatment field, with very minor scatter effects at the edges in some cases.

One option that some patients ask about is scalp cooling (cold cap therapy). This technique, which is available through many NHS trusts for chemotherapy patients, works by reducing blood flow to the scalp during treatment, limiting drug exposure to follicles. It is not relevant for radiotherapy, where the mechanism of hair loss is direct radiation to the follicle rather than a circulating drug.

NHS Support for Radiotherapy Patients#

If you lose hair during cancer treatment, you may be eligible for an NHS wig. In England, standard NHS charges apply unless you qualify for an exemption through the NHS Low Income Scheme or certain benefits. Provision differs across the devolved nations: patients in Scotland, Wales, and Northern Ireland should check with their clinical team. The NHS Business Services Authority has up-to-date information on charges and exemptions.

Macmillan Cancer Support and Cancer Research UK both offer practical guidance and emotional support for patients experiencing hair loss during treatment. Macmillan's specialist nurse helpline (0808 808 00 00) is worth knowing about if you're struggling.

If you have concerns about a treatment-related side effect, you can also report it via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

Hormonal Causes of Hair Loss#

Radiotherapy is one cause of hair loss, but for many people reading this, the more relevant question is about hormones. Hormonal hair loss is extremely common and often goes unrecognised for months because the shedding tends to be gradual rather than sudden.

To understand how hormones affect hair, it helps to know the basics of the hair growth cycle. Each follicle cycles through a growing phase (anagen, lasting 2 to 7 years), a transitional phase (catagen, around 2 to 3 weeks), a resting phase (telogen, roughly 3 months), and finally a shedding phase (exogen). On average, 80 to 90% of hairs are in the anagen phase at any given time. When something disrupts this cycle, more hairs shift into the resting or shedding phase simultaneously, and that's when you notice the change.

Androgens and DHT#

Dihydrotestosterone (DHT) is the hormone most closely associated with pattern hair loss in both men and women. DHT is converted from testosterone by an enzyme called 5-alpha reductase. In people who are genetically sensitive to DHT, it binds to receptors in hair follicles and causes them to miniaturise gradually, producing finer and shorter strands until growth stops altogether.

In men, this presents as a receding hairline or crown thinning. In women, it more commonly causes diffuse thinning along the parting rather than a distinct receding hairline. This is called female pattern hair loss, or androgenetic alopecia.

Oestrogen#

Oestrogen has a broadly protective effect on hair. It prolongs the anagen (growth) phase and tends to counterbalance the effects of androgens. During pregnancy, high oestrogen levels often cause hair to look thicker and fuller. After delivery, oestrogen drops sharply, and many women experience significant shedding 2 to 3 months later. This is a form of telogen effluvium and is temporary, though it can be alarming.

The same mechanism plays out during perimenopause and menopause as oestrogen levels decline. With less oestrogen to buffer the effects of androgens, DHT can exert more influence on follicles, leading to thinning that feels very different from the temporary shedding of postpartum hair loss.

Progesterone#

Progesterone helps to inhibit 5-alpha reductase, which means it effectively reduces DHT production. When progesterone levels drop, as happens during the luteal phase of the cycle, perimenopause, or in conditions like PCOS, DHT's influence increases. Low progesterone is also associated with elevated cortisol, which can further push follicles into the resting phase.

Thyroid Hormones#

Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) can cause diffuse hair shedding. Thyroid hormones regulate the pace of many cellular processes, including the hair cycle. When thyroid function is disrupted, follicles can lose their normal rhythm. The good news is that once thyroid levels are corrected with appropriate treatment, hair usually recovers, though this can take several months.

Common Conditions That Cause Hormonal Hair Loss#

PCOS#

Polycystic ovary syndrome (PCOS) is one of the most common causes of hormonal hair loss in women under 40. PCOS involves elevated androgen levels, particularly DHT, which can cause follicle miniaturisation and thinning. Around 70% of women with PCOS also have insulin resistance, which further compounds the problem by reducing Sex Hormone-Binding Globulin (SHBG), leaving more free testosterone to act on follicles.

Menopause and Perimenopause#

As oestrogen and progesterone decline during perimenopause and menopause, the relative influence of androgens increases. Hair loss during this life stage is extremely common and often emotionally difficult, partly because it coincides with other visible changes and partly because it feels less talked about than hot flushes or sleep disruption.

Hormone replacement therapy (HRT) is increasingly discussed as a potential option for managing menopause-related hair thinning, though it is not specifically licensed for hair loss. Women who are already considering HRT for other menopausal symptoms may find their hair responds positively. This is worth discussing with a GP who can review your individual circumstances.

Nutritional Deficiencies#

Iron deficiency (particularly low ferritin), vitamin D deficiency, and low B12 can all contribute to or worsen hormonally-driven hair loss. This is particularly relevant for women with heavy periods or following significant dietary changes. If you're experiencing hair loss alongside fatigue or other symptoms, it's worth asking your GP for a blood panel that includes ferritin, thyroid function, B12, and vitamin D before assuming the cause is purely hormonal.

Medications That Cause Hair Loss#

Beyond radiotherapy and hormonal changes, a surprisingly wide range of common prescription medications list hair loss as a side effect. Most drug-induced hair loss is temporary and resolves once the medication is stopped or changed, though this isn't always possible if the drug is essential for another condition.

The two main types of drug-induced hair loss are telogen effluvium (where medication pushes follicles prematurely into the resting phase, causing diffuse shedding 2 to 3 months after starting the drug) and anagen effluvium (where drugs disrupt the active growth phase, causing more rapid and severe shedding, as seen with chemotherapy).

Here are the medication categories most commonly linked to hair loss:

Beta-blockers and antihypertensives: Drugs like atenolol, metoprolol, and propranolol can trigger telogen effluvium. ACE inhibitors such as lisinopril and ramipril are also associated with hair shedding, though the mechanism is less well understood.

Statins: Atorvastatin and simvastatin are occasionally linked to hair thinning. The evidence is limited and the association appears uncommon, but it does appear in case reports and patient databases.

Anticoagulants: Warfarin and, to a lesser extent, some direct oral anticoagulants (DOACs) such as rivaroxaban can cause telogen effluvium. Hair loss typically appears 2 to 4 months after starting therapy.

Anticonvulsants: Valproate (sodium valproate) is one of the most commonly reported causes of drug-induced hair loss. Other anticonvulsants including carbamazepine and lamotrigine have also been implicated.

Antidepressants: SSRIs including fluoxetine and sertraline, as well as SNRIs such as venlafaxine, have been associated with hair shedding. This is relatively uncommon and does not affect everyone who takes them, but it's worth knowing about.

Testosterone and anabolic agents: Any medication that raises testosterone levels, including testosterone replacement therapy (TRT) and anabolic steroids, can accelerate male pattern baldness by increasing DHT conversion.

If you suspect a medication is contributing to your hair loss, do not stop taking it without speaking to your GP first. In many cases, an alternative drug from the same class can be trialled, or the dose can be adjusted. Stopping some medications abruptly (particularly anticonvulsants or antidepressants) carries real risks.

Treatment Options for Male Pattern Hair Loss#

If your hair loss is related to DHT and pattern baldness rather than a medication or systemic condition, there are evidence-based treatments that can help.

Finasteride (1mg daily) works by blocking 5-alpha reductase, which reduces DHT production by around 70%. Clinical trials show it significantly slows hair loss and, in many men, promotes measurable regrowth particularly at the crown. It needs to be taken consistently; stopping it reverses any benefit within 6 to 12 months.

Minoxidil (applied topically to the scalp) works through a different mechanism, promoting blood flow to follicles and prolonging the anagen phase. It's available as a liquid or foam and is used twice daily. Regaine is the most well-known brand in the UK, available in 60ml (£33.60) and 180ml (£79.99) formulations from Totiva.

Many clinicians recommend combining both treatments because they work through different pathways. Finasteride at Totiva starts from £14.99 for a 28-day supply (1mg tablets), with an 84-tablet pack available for £41.99.

Totiva's hair loss service is for men only. If you're a woman experiencing hair loss, your GP is the right starting point for a hormonal blood panel, thyroid check, and referral to a dermatologist or trichologist if needed.

If you're a man who's noticed your hairline shifting or thinning at the crown, earlier treatment tends to give better results. You can start a free consultation with Totiva's pharmacist team, who will review your history and recommend the most appropriate treatment without requiring a GP visit first.

When to See a GP#

Not all hair loss needs a specialist, but some does. See your GP if:

• Hair loss is sudden, patchy, or accompanied by scalp inflammation or scarring
• You're losing hair in clumps rather than gradual thinning
• You have other symptoms suggesting a thyroid problem, anaemia, or autoimmune condition
• You're a woman experiencing significant thinning and haven't had a hormonal blood panel done
• You suspect a medication you're taking is the cause, so the prescribing clinician can review alternatives

When you see your GP, it's reasonable to ask for ferritin, full blood count, thyroid function tests (TSH, free T4), and, for women, a hormonal profile including testosterone and SHBG. These are standard tests that can rule out or confirm most common treatable causes.

For men with straightforward male pattern baldness, an online consultation is often sufficient to get started. Totiva's hair loss service offers pharmacist-led assessments and prescription treatments dispatched discreetly to your door.