Does DHT blockers cause erectile dysfunction? This question concerns many men considering treatment for male pattern hair loss. DHT blockers, particularly finasteride and dutasteride, work by reducing dihydrotestosterone levels to slow hair loss progression. However, clinical evidence and UK regulatory guidance confirm that these medications can cause sexual side effects, including erectile dysfunction, in a subset of users. Understanding the relationship between DHT blockers and sexual function, recognising warning signs, and knowing when to seek medical advice are essential for making informed treatment decisions. This article examines the evidence, explores management strategies, and provides guidance aligned with MHRA safety updates and NHS clinical pathways.

What Are DHT Blockers and How Do They Work?

DHT blockers are medications or supplements designed to reduce levels of dihydrotestosterone (DHT), a potent androgen hormone derived from testosterone. DHT plays a significant role in male pattern hair loss (androgenetic alopecia) by miniaturising hair follicles on the scalp, leading to progressive thinning and eventual hair loss. By inhibiting the enzyme 5-alpha reductase, which converts testosterone to DHT, these medications can slow or halt hair loss progression.

The most commonly prescribed DHT blocker in the UK is finasteride (available as a 1mg prescription-only medicine for hair loss or 5mg for benign prostatic hyperplasia). Finasteride specifically inhibits the type II isoform of 5-alpha reductase, reducing DHT levels in the scalp and bloodstream by approximately 60–70%. Another medication, dutasteride (0.5mg), blocks both type I and type II isoforms, achieving even greater DHT suppression of around 90%. Whilst dutasteride is licensed only for prostate enlargement in the UK, it is sometimes prescribed off-label for hair loss.

Beyond prescription medications, various natural supplements and topical treatments claim DHT-blocking properties, including saw palmetto, pumpkin seed oil, and green tea extract. However, the evidence supporting these alternatives remains limited compared to pharmaceutical options.

How DHT blockers affect the body: By reducing DHT levels, these medications can influence various androgen-dependent processes throughout the body. Whilst this mechanism effectively addresses hair loss, it may also impact other tissues where DHT plays a physiological role, including the prostate, skin, and potentially sexual function. It typically takes 3-6 months to see initial benefits, and continued use is required to maintain results. Understanding this broader hormonal influence is essential when considering treatment options and potential side effects.

Which DHT Blockers Are Linked to Sexual Side Effects?

Finasteride is the DHT blocker most extensively studied regarding sexual side effects. Clinical trials and post-marketing surveillance have established that finasteride can cause erectile dysfunction, reduced libido, and ejaculatory disorders in a subset of users. According to the UK product information, sexual side effects occur in 1-10% of users at the 1mg dose used for hair loss.

The Medicines and Healthcare products Regulatory Agency (MHRA) has highlighted these concerns in a 2024 Drug Safety Update. The finasteride patient information leaflet now includes warnings about sexual dysfunction that may persist after stopping treatment. Patients are advised to stop finasteride and seek medical help if they experience mood changes or suicidal thoughts. A patient alert card is now provided with finasteride to highlight these risks.

Dutasteride, with its more complete DHT suppression, carries a similar risk profile for sexual side effects. According to its UK product information, erectile dysfunction occurs in 1-10% of users, decreased libido in 1-10%, and ejaculation disorders in 1-10% when used at the 0.5mg dose for prostate conditions. Evidence specifically examining its use for hair loss is more limited as this remains an off-label use.

Natural DHT blockers such as saw palmetto have limited robust clinical data regarding sexual side effects. Small studies suggest these supplements may have fewer sexual side effects, but the evidence base is insufficient to draw definitive conclusions about their safety profile. The lack of regulatory oversight for most supplements also means potency and purity can vary significantly between products, unless they have Traditional Herbal Registration (THR) status.

It is worth noting that erectile dysfunction has multiple potential causes, and establishing a direct causal relationship with DHT blockers can be challenging, particularly given that anxiety about hair loss itself may impact sexual function.

If you experience side effects from any medication, you can report them through the MHRA Yellow Card scheme.

Managing Erectile Dysfunction While Using DHT Blockers

If you experience erectile dysfunction whilst taking a DHT blocker, several management strategies may help, though any changes should be discussed with your GP or prescribing clinician first.

Dose adjustment or treatment breaks: Some men find that reducing the finasteride dose or frequency may reduce side effects whilst maintaining some hair loss benefit. However, this approach lacks robust clinical evidence, may reduce effectiveness, and represents off-label use that should only be attempted under medical supervision. Temporary treatment breaks allow assessment of whether symptoms resolve, helping establish causality.

Switching medications: If sexual side effects are problematic with oral DHT blockers, your doctor might discuss alternative hair loss treatments. Topical minoxidil works through a different mechanism that does not affect DHT levels or sexual function. The exact mechanism by which minoxidil promotes hair growth is not fully understood, but it does not involve hormonal pathways. Low-level laser therapy and platelet-rich plasma (PRP) injections represent other non-hormonal options, though evidence for their effectiveness varies and they are typically not available on the NHS.

Addressing erectile dysfunction directly: If you wish to continue DHT blocker therapy, erectile dysfunction can often be managed with phosphodiesterase-5 (PDE5) inhibitors such as sildenafil, tadalafil, or vardenafil. These medications are available on NHS prescription for certain conditions or can be obtained privately. Your GP will assess your suitability, including cardiovascular risk factors, and screen for contraindications. PDE5 inhibitors must not be taken with nitrate medications or riociguat, and caution is needed if you take alpha-blockers.

Psychological support: Sexual dysfunction can have significant psychological impact, and anxiety about side effects may itself worsen symptoms. Cognitive behavioural therapy (CBT) or psychosexual counselling, available through NHS talking therapies services, may be beneficial, particularly if anxiety or relationship concerns are contributing factors.

Lifestyle modifications: Maintaining cardiovascular health through regular exercise, healthy diet, adequate sleep, limiting alcohol, and avoiding smoking supports erectile function regardless of medication use. These measures are recommended in the NICE Clinical Knowledge Summary for managing erectile dysfunction.

When to Speak to Your GP About Sexual Side Effects

You should contact your GP or prescribing clinician if you experience any new or worsening sexual symptoms whilst taking a DHT blocker. Early discussion is important because it allows proper assessment, helps establish whether the medication is responsible, and enables timely intervention if needed.

Specific situations requiring medical review include:

• New-onset erectile dysfunction that develops after starting a DHT blocker and persists beyond the initial weeks

• Significant reduction in libido that affects your quality of life or relationships

• Ejaculatory problems such as reduced ejaculate volume, delayed ejaculation, or inability to ejaculate

• Persistent symptoms that continue after stopping the medication

• Psychological distress related to sexual side effects, including anxiety, low mood, or relationship difficulties

• Any other concerning symptoms such as breast tenderness, gynaecomastia (breast tissue development), or testicular discomfort

• Mood changes or suicidal thoughts – stop taking finasteride immediately and seek urgent medical help

Your GP will take a thorough history to assess the timeline of symptoms, exclude other potential causes of erectile dysfunction (such as cardiovascular disease, diabetes, hormonal disorders, or other medications), and discuss your treatment priorities. They may perform a physical examination and arrange blood tests to check testosterone levels, prolactin, thyroid function, glucose, and lipid profile if clinically indicated.

For persistent or complex sexual side effects, your GP may refer you to a urologist, andrologist, or psychosexual service for specialist assessment and management.

Important considerations: Be open about the impact on your quality of life—sexual health is an important aspect of overall wellbeing, and healthcare professionals are accustomed to discussing these concerns.

If you experience sudden, complete loss of erectile function, particularly if accompanied by other symptoms such as chest pain, severe headache, or neurological changes, seek urgent medical attention, as this may indicate an unrelated serious condition requiring immediate assessment.

If you suspect side effects from any medication, you can report them through the MHRA Yellow Card scheme.

Frequently Asked Questions