How long does an erection last with tadalafil? Many men prescribed this medication wonder about its effects on erection duration. Tadalafil, a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for erectile dysfunction, facilitates normal erectile responses rather than causing prolonged erections. Whilst the medication remains active in the body for up to 36 hours, individual erections typically last for a natural duration—until ejaculation or the end of sexual arousal. Understanding how tadalafil works, its duration of action, and what to expect can help men use this treatment safely and effectively under medical supervision.

How Tadalafil Works for Erectile Dysfunction

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for the treatment of erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and ED with BPH. It works by enhancing the natural erectile response to sexual stimulation rather than causing spontaneous erections. When a man is sexually aroused, nerve signals trigger the release of nitric oxide in the penile tissue, which activates an enzyme called guanylate cyclase. This enzyme increases levels of cyclic guanosine monophosphate (cGMP), a chemical messenger that relaxes smooth muscle in the blood vessels of the penis, allowing increased blood flow and facilitating an erection.

Under normal circumstances, the enzyme PDE5 breaks down cGMP, which naturally limits the duration of an erection. Tadalafil inhibits PDE5, thereby preventing the premature breakdown of cGMP and allowing the smooth muscle relaxation and increased blood flow to be maintained for longer periods during sexual activity. It is important to understand that tadalafil does not cause erections without sexual stimulation — the medication simply makes it easier to achieve and maintain an erection when aroused.

Tadalafil is available in the UK under various brand names, including Cialis, and as generic formulations. It is prescribed in different doses depending on whether it is used on an as-needed basis (typically 10 mg or 20 mg taken before anticipated sexual activity) or as a daily low-dose treatment (2.5 mg or 5 mg). NHS prescribing arrangements for erectile dysfunction vary across the UK and may depend on local policies, specific indications, and individual circumstances. The medication is also widely available through private prescription. The Medicines and Healthcare products Regulatory Agency (MHRA) regulates tadalafil, and it has been extensively studied and is considered effective and generally well-tolerated for most men with erectile dysfunction.

Duration of Tadalafil's Effects in the Body

Tadalafil is distinguished from other PDE5 inhibitors by its notably long duration of action in the body. After oral administration, tadalafil is absorbed relatively quickly, with peak plasma concentrations typically reached within 30 minutes to 6 hours, though the average is around 2 hours. The medication can begin to work within 30 to 60 minutes of taking it, though some men may notice effects sooner or later depending on individual factors.

The most significant characteristic of tadalafil is its extended half-life of approximately 17.5 hours. This means that it takes this length of time for the concentration of the drug in the bloodstream to reduce by half. As a result, tadalafil remains active in the body for a considerably longer period compared to other ED medications such as sildenafil (Viagra), which has a half-life of 3 to 5 hours. Clinical studies have demonstrated that tadalafil can remain effective for up to 36 hours after a single dose, providing an extended window of opportunity for sexual activity.

This extended window of effectiveness does not mean that an erection will last for 36 hours. Rather, it means that during this period, a man may find it easier to achieve and maintain erections in response to sexual stimulation. The prolonged duration offers greater spontaneity and flexibility in timing sexual activity, as there is less pressure to coordinate intimacy within a narrow timeframe. For men taking the daily low-dose formulation, steady-state plasma concentrations are achieved after approximately 5 days of regular use, providing continuous support for erectile function without the need to time doses around sexual activity.

How Long Does an Erection Last with Tadalafil

A common misconception about tadalafil is that it causes prolonged or continuous erections. In reality, tadalafil facilitates normal erectile responses to sexual stimulation , and individual erections typically last for a duration similar to what would be expected without medication — generally until ejaculation or the cessation of sexual arousal. The medication does not fundamentally alter the natural erectile cycle; rather, it makes it easier to achieve erections and may help maintain firmness during sexual activity.

The duration of an erection with tadalafil varies considerably between individuals and depends on many factors including age, overall health, the cause and severity of erectile dysfunction, and the level of sexual arousal. There is no standard duration that can be expected, as erectile response remains highly individualised even with medication. The key difference when using tadalafil is that during the 36-hour window when the medication remains active, men may find it easier to achieve subsequent erections with renewed sexual stimulation.

It is important to emphasise that tadalafil does not cause constant or uncontrolled erections. The medication requires sexual arousal to be effective, and erections should resolve normally after sexual activity concludes. Men using tadalafil should experience improved erectile function without the erection persisting beyond the period of sexual activity. If an erection does last longer than 4 hours or becomes painful, this may indicate a rare but serious condition called priapism, which requires immediate medical attention. However, under normal circumstances, tadalafil supports natural erectile function rather than creating abnormally prolonged erections.

Factors That Affect Erection Duration

Several factors can influence how long an erection lasts when using tadalafil, and individual responses to the medication can vary considerably. Age is one significant factor — older men may experience different responses compared to younger men due to age-related changes in vascular health, testosterone levels, and overall cardiovascular function. The underlying cause and severity of erectile dysfunction also play a role; men with mild ED may respond differently to those with more severe vascular or neurological causes.

Dosage is another important consideration. Higher doses of tadalafil (20 mg) may produce more pronounced effects compared to lower doses (10 mg or 2.5-5 mg daily), though this does not necessarily translate to longer individual erections. Rather, higher doses may improve erectile rigidity and the ease of achieving erections. The presence of other medical conditions — particularly cardiovascular disease, diabetes, hypertension, or neurological disorders — can affect both erectile function and response to treatment. Men with these conditions may experience variable results.

Lifestyle factors significantly impact erectile function and medication effectiveness. Alcohol consumption can impair erectile function and may reduce the effectiveness of tadalafil; substantial alcohol intake should be avoided as it may increase the risk of dizziness and orthostatic hypotension. Smoking damages blood vessels and can compromise erectile function. Diet, exercise, and overall cardiovascular health all contribute to erectile performance. Psychological factors such as anxiety, stress, depression, or relationship issues can affect arousal and erectile response, even when taking medication.

Drug interactions may also influence tadalafil's effects. Nitrates (used for angina) and guanylate cyclase stimulators (such as riociguat) are absolutely contraindicated with tadalafil due to the risk of dangerous blood pressure drops. Alpha-blockers, certain antifungals, and other medications can interact with tadalafil. Strong CYP3A4 inhibitors (such as ketoconazole, ritonavir) and grapefruit juice may increase tadalafil levels, while CYP3A4 inducers (such as rifampicin) may reduce effectiveness. Unlike some other ED medications, tadalafil can be taken with or without food, as its absorption is not significantly affected by meals.

When to Seek Medical Help for Prolonged Erections

Priapism is a rare but serious medical emergency characterised by a persistent, often painful erection lasting more than 4 hours without sexual stimulation or that does not subside after sexual activity has ended. Although rare with tadalafil, priapism requires immediate medical attention to prevent permanent damage to the penile tissue and long-term erectile dysfunction. There are two types: ischaemic (low-flow) priapism, which is a medical emergency, and non-ischaemic (high-flow) priapism, which is less urgent but still requires assessment.

You should seek immediate medical help — either by attending your nearest Accident & Emergency department or calling 999 — if you experience an erection lasting longer than 4 hours, particularly if it is painful. Do not delay seeking help due to embarrassment; healthcare professionals are accustomed to treating this condition, and prompt treatment is essential to preserve erectile function. Early intervention, typically within 4 to 6 hours, significantly improves outcomes. Treatment may involve draining blood from the penis, administering medications to constrict blood vessels, or in rare cases, surgical intervention.

Other situations warranting medical attention include sudden loss of vision or hearing while taking tadalafil, severe dizziness or fainting, chest pain during sexual activity, or allergic reactions such as rash, swelling of the face or throat, or difficulty breathing. If you experience chest pain during sexual activity, you should stop immediately, seek medical advice, and importantly, do not take nitrate medications. Always inform healthcare providers that you have taken tadalafil, as nitrates must not be administered within at least 48 hours of PDE5 inhibitor use. Men with certain risk factors for priapism — including sickle cell disease, leukaemia, multiple myeloma, or anatomical penile abnormalities — should discuss these with their GP before using tadalafil, as they may require closer monitoring or alternative treatments.

Safe Use of Tadalafil: NHS Guidance

The NHS and NICE provide clear guidance on the safe and appropriate use of tadalafil for erectile dysfunction. Tadalafil should only be used under medical supervision following proper assessment by a GP or specialist. Before prescribing, healthcare professionals should take a comprehensive medical and sexual history, assess cardiovascular risk, and review current medications to identify potential contraindications or interactions. Men with significant cardiovascular disease may require specialist assessment before tadalafil can be safely prescribed, and a cardiovascular risk stratification approach is recommended before resuming sexual activity.

Dosing recommendations vary depending on individual circumstances. For on-demand use, the typical starting dose is 10 mg taken at least 30 minutes before anticipated sexual activity, which can be adjusted to 20 mg or reduced to 5 mg based on efficacy and tolerability. The maximum recommended dosing frequency is once daily. For daily use, lower doses of 2.5 mg or 5 mg are taken at approximately the same time each day, regardless of sexual activity timing. Men with moderate kidney impairment may require dose adjustments, while once-daily dosing is not recommended in severe renal or hepatic impairment. Tadalafil should be avoided in severe hepatic impairment.

Important safety considerations include absolute contraindications: tadalafil must never be taken with nitrates, nitric oxide donors (such as amyl nitrite), or guanylate cyclase stimulators (such as riociguat) due to the risk of severe hypotension. Caution is advised with alpha-blockers, and these should be stable before starting tadalafil. Men should be counselled about potential side effects, which commonly include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion. These are usually mild and transient. Suspected side effects should be reported via the MHRA Yellow Card scheme.

The NHS emphasises that lifestyle modifications should accompany pharmacological treatment where appropriate. This includes smoking cessation, reducing alcohol intake, maintaining a healthy weight, regular exercise, and managing underlying conditions such as diabetes and hypertension. Psychological factors should also be addressed, and relationship counselling may be beneficial in some cases. Tadalafil should be stored safely out of reach of children, and men should be advised not to share their medication with others. Regular review with a healthcare professional ensures ongoing safety and effectiveness of treatment.

Frequently Asked Questions