Tadalafil, a phosphodiesterase type 5 (PDE5) inhibitor, is available in the UK in several milligram strengths tailored to different treatment needs. For erectile dysfunction, tadalafil comes in 2.5 mg, 5 mg, 10 mg, and 20 mg tablets, whilst benign prostatic hyperplasia is treated exclusively with 5 mg daily. The appropriate dose depends on whether you require daily or on-demand therapy, your individual response, and clinical factors such as kidney function and concurrent medications. Understanding these dosage options helps ensure safe, effective treatment under medical supervision.

Understanding Tadalafil Dosage Strengths

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for treating erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). The medication is available in several dosage strengths, each designed for specific treatment regimens and clinical indications. Understanding these different milligram options helps patients and healthcare professionals select the most appropriate dose for individual circumstances.

Available strengths in the UK include:

• 2.5 mg tablets (daily use)

• 5 mg tablets (daily use or on-demand)

• 10 mg tablets (on-demand use)

• 20 mg tablets (on-demand use)

These specific strengths are approved in the UK based on clinical trials demonstrating their efficacy and safety profiles. The lower doses (2.5 mg and 5 mg) are typically prescribed for daily administration, providing continuous therapeutic levels in the bloodstream. Higher doses (10 mg and 20 mg) are reserved for on-demand use, taken prior to anticipated sexual activity.

Tadalafil's mechanism of action involves selective inhibition of PDE5 enzymes in the corpus cavernosum, enhancing the effects of nitric oxide and promoting smooth muscle relaxation. This facilitates increased blood flow to the penis during sexual stimulation. The medication's long half-life of approximately 17.5 hours distinguishes it from other PDE5 inhibitors, allowing for greater dosing flexibility and effects lasting up to 36 hours. Tadalafil can be taken with or without food, as food does not significantly affect its absorption. Patients should never adjust their prescribed dose without consulting their GP or prescribing clinician, as dosage requirements vary based on individual response, tolerability, and concurrent medical conditions.

Standard Tadalafil Doses for Erectile Dysfunction

For erectile dysfunction, the standard on-demand tadalafil dose is 10 mg, taken at least 30 minutes before sexual activity. This represents the initial dose for most men without contraindications or significant comorbidities. The 10 mg strength provides an effective balance between therapeutic benefit and tolerability for the majority of patients presenting with ED.

Depending on individual response and tolerability, the dose may be adjusted by a healthcare professional. If the 10 mg dose proves insufficient, it can be increased to 20 mg, which represents the maximum recommended single dose for on-demand use. Conversely, if patients experience adequate response or encounter adverse effects at 10 mg, the dose may be reduced to 5 mg. These adjustments should always be made under medical supervision following assessment of treatment response.

Tadalafil demonstrates dose-dependent efficacy, with clinical trials showing improved erectile function scores at higher doses. However, adverse effects also increase with dose escalation. The medication should not be taken more than once within a 24-hour period, regardless of the strength used. Patients should be counselled that tadalafil requires sexual stimulation to be effective—it does not cause spontaneous erections.

Important considerations for ED dosing:

• Allow adequate time for the medication to take effect (30–60 minutes, peak effect around 2 hours)

• Effects may last up to 36 hours

• Avoid excessive alcohol consumption, which may impair response

• Can be taken with or without food

• Maximum frequency: once daily

Patients who do not respond adequately to the maximum dose should consult their GP for review, as underlying cardiovascular, hormonal, or psychological factors may require investigation. Patients should seek urgent medical attention if they experience chest pain during sexual activity, an erection lasting more than 4 hours, or sudden vision or hearing loss.

Daily vs On-Demand Tadalafil: Dosage Differences

Tadalafil offers two distinct dosing regimens for erectile dysfunction: daily low-dose therapy and on-demand higher-dose therapy. These approaches suit different patient preferences, sexual activity patterns, and lifestyle considerations. Understanding the dosage differences between these regimens helps patients and clinicians select the most appropriate treatment strategy.

Daily tadalafil is prescribed at 5 mg once daily, taken at approximately the same time each day regardless of sexual activity timing. If this dose is not tolerated, it may be reduced to 2.5 mg. This regimen maintains steady therapeutic plasma levels, allowing for spontaneity in sexual activity without planning around medication timing. Daily dosing particularly benefits men who engage in sexual activity more than twice weekly or who prefer not to plan medication around intimacy.

The daily regimen's pharmacokinetic profile ensures continuous PDE5 inhibition. Patients must understand that daily tadalafil requires consistent adherence—missing doses may reduce therapeutic effectiveness. The ongoing need for daily treatment should be reassessed periodically.

On-demand tadalafil uses higher strengths (10 mg or 20 mg) taken as needed before sexual activity. This approach suits men with less frequent sexual activity or those who prefer episodic treatment. The on-demand regimen offers flexibility in terms of treatment days whilst avoiding daily medication exposure.

Both regimens are effective when used appropriately, with choice depending on individual circumstances, cost considerations, and patient preference. Healthcare professionals should discuss both options during initial consultations, considering factors such as relationship status, sexual activity frequency, and patient lifestyle when recommending a specific dosing strategy.

Tadalafil Dosing for Benign Prostatic Hyperplasia

Tadalafil is also licensed for treating the signs and symptoms of benign prostatic hyperplasia (BPH), a common condition affecting older men characterised by lower urinary tract symptoms (LUTS). For this indication, the dosing differs significantly from erectile dysfunction treatment, reflecting different therapeutic objectives and the medication's effects on prostatic and bladder smooth muscle.

The standard and only recommended dose for BPH is 5 mg once daily. This dose has been established through clinical trials demonstrating improvements in International Prostate Symptom Score (IPSS) and urinary flow rates. Unlike ED treatment, there is no dose escalation for BPH—5 mg daily represents both the starting and maintenance dose. The medication should be taken at approximately the same time each day to maintain consistent plasma levels.

Tadalafil's mechanism in BPH involves relaxation of smooth muscle in the prostate and bladder neck through PDE5 inhibition, reducing urethral resistance and improving urinary flow. Clinical studies show symptom improvement typically becomes apparent within 1–2 weeks, with maximum benefits observed after several weeks of continuous therapy. Patients should be counselled that BPH treatment requires ongoing daily administration—it is not an on-demand therapy.

Key points for BPH dosing:

• Fixed dose: 5 mg daily only

• Requires consistent daily administration

• Caution with alpha-blockers due to potential hypotension risk

• Suitable for men with both ED and BPH (dual indication)

For men experiencing both erectile dysfunction and BPH symptoms, the 5 mg daily dose addresses both conditions simultaneously, offering therapeutic convenience. However, this dual indication should be confirmed by appropriate clinical assessment. Patients not responding adequately to tadalafil for BPH should be reviewed for alternative or additional treatments, as NICE guidance (NG97) recommends considering alpha-blockers or 5-alpha reductase inhibitors depending on prostate size and symptom severity.

Factors That Influence Your Tadalafil Dose

Several clinical and individual factors influence the appropriate tadalafil dose for each patient. Healthcare professionals consider these variables when initiating treatment and making subsequent dose adjustments, ensuring both efficacy and safety are optimised for individual circumstances.

Age and hepatic function significantly impact tadalafil metabolism. The medication is primarily metabolised by hepatic CYP3A4 enzymes, meaning patients with moderate hepatic impairment should not exceed 10 mg as an on-demand dose. Daily dosing is not recommended in hepatic impairment. For severe hepatic impairment, tadalafil use is not recommended due to limited clinical data. Elderly patients (over 65 years) generally do not require dose adjustment unless other factors necessitate modification.

Renal function also affects dosing recommendations. For patients with mild to moderate renal impairment (creatinine clearance 30–80 mL/min), standard doses may be used, though starting with lower strengths is often prudent. In severe renal impairment (creatinine clearance below 30 mL/min), maximum on-demand dose is 10 mg no more often than every 72 hours, and once-daily dosing is not recommended. For patients on haemodialysis, the maximum on-demand dose is 5 mg.

Concurrent medications represent critical considerations. Strong CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole) significantly increase tadalafil plasma levels, necessitating dose reduction. When used with these medications, maximum doses should not exceed 10 mg every 72 hours for on-demand use, whilst daily dosing requires careful consideration. CYP3A4 inducers (such as rifampicin, carbamazepine) may reduce tadalafil efficacy. Alpha-blockers used concomitantly increase hypotension risk; patients should be stable on alpha-blocker therapy before starting tadalafil.

Cardiovascular status influences prescribing decisions. Patients with cardiovascular disease should be assessed for fitness for sexual activity before tadalafil prescription. Tadalafil is contraindicated in patients taking nitrates or nitric oxide donors (including recreational 'poppers') due to severe hypotension risk. It is also contraindicated with guanylate cyclase stimulators such as riociguat.

Additional factors affecting dosing include:

• Response to initial treatment (efficacy and tolerability)

• Severity of erectile dysfunction

• Frequency of sexual activity

• Patient preference and lifestyle

• Cost and accessibility considerations

Patients should inform their healthcare provider of all medications, supplements, and medical conditions before starting tadalafil. Any adverse effects, inadequate response, or changes in health status warrant medical review for potential dose adjustment. Self-adjusting doses without medical guidance may compromise safety and treatment outcomes. Suspected side effects should be reported via the MHRA Yellow Card scheme.

Frequently Asked Questions