Tadalafil Priapism: What to Do & When to Seek Help

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Tadalafil Priapism: Understanding the Risk, What to Do, and Your Options

Published: 17 October 2026

Tadalafil priapism—a prolonged, painful erection lasting more than four hours—is a rare but serious side effect of tadalafil (generic Cialis) that requires immediate medical attention. While tadalafil is a safe and effective treatment for erectile dysfunction for most men, understanding this uncommon complication helps you recognise the warning signs and act quickly if needed. This page explains how common priapism is with tadalafil, why it happens, what to do if an erection won't go down, and alternative ED treatments you can discuss with your prescriber.

How Common Is Tadalafil Priapism?

Priapism is a very rare side effect of tadalafil. Clinical trials and post-marketing surveillance suggest it affects fewer than 1 in 1,000 men taking the medicine [4]. The British National Formulary lists priapism as an uncommon or rare adverse effect across all PDE5 inhibitors, including tadalafil, sildenafil, vardenafil, and avanafil [3][4][5][6].

Although the risk is low, it is important to be aware of it because priapism is a medical emergency. If an erection lasts longer than four hours, blood becomes trapped in the penis, which can damage the tissue and lead to permanent erectile dysfunction if not treated promptly [1][2]. The absolute number of cases is small, but the consequences of delayed treatment can be serious.

Certain factors may slightly increase your risk, including higher doses of tadalafil, taking other medicines that affect blood flow, or having conditions such as sickle cell disease, leukaemia, or multiple myeloma. Your prescriber will review your medical history during your online consultation to ensure tadalafil is suitable for you and to minimise any risks.

Why Does Priapism Happen with Tadalafil?

Tadalafil works by inhibiting an enzyme called phosphodiesterase type 5 (PDE5), which helps relax the smooth muscle in the blood vessels of the penis [4]. This increases blood flow during sexual stimulation, making it easier to achieve and maintain an erection. Normally, after ejaculation or when arousal subsides, blood drains away and the erection goes down.

In priapism, the normal drainage mechanism fails, and blood remains trapped in the penis even without ongoing sexual stimulation. This can happen if the balance between blood inflow and outflow is disrupted. Tadalafil's long duration of action—up to 36 hours—means it stays in your system longer than shorter-acting PDE5 inhibitors, which may theoretically prolong any abnormal erection, though the overall risk remains very low [4].

Priapism can also occur if tadalafil is combined with other medicines or substances that affect blood flow or metabolism, or if you have an underlying blood disorder. This is why it is essential to declare all your current medicines, supplements, and health conditions during your consultation. Your prescriber will check for any interactions or contraindications before approving tadalafil.

Drug Interactions That May Increase Risk

Certain medicines can raise tadalafil levels in your blood, potentially increasing the risk of side effects including priapism. Potent CYP3A4 inhibitors—such as ritonavir, cobicistat (found in some HIV medicines), ketoconazole, itraconazole, and clarithromycin—slow the breakdown of tadalafil, leading to higher concentrations [4]. If you take any of these, your prescriber will reduce your tadalafil dose or choose an alternative ED treatment.

Never take tadalafil with nitrates (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), as this combination can cause a dangerous drop in blood pressure [4]. Alpha-blockers used for prostate symptoms (such as tamsulosin or doxazosin) can also lower blood pressure when combined with tadalafil; you should be stable on the alpha-blocker and start on the lowest tadalafil dose [4]. Always list every medicine you take, including over-the-counter products and herbal supplements, during your consultation.

How Long Does Tadalafil Priapism Last?

By definition, priapism is an erection that lasts longer than four hours without sexual stimulation or that remains painful after that time [1][2]. If left untreated, priapism can persist for many hours or even days, causing progressive damage to the erectile tissue. The longer the blood remains trapped, the greater the risk of permanent scarring and loss of erectile function.

If you seek medical help promptly—ideally within four hours—doctors can usually drain the trapped blood and reverse the condition with minimal long-term effects. Treatment may involve draining blood from the penis with a needle and syringe, injecting a medicine to constrict blood vessels, or, in rare cases, surgery to restore normal blood flow [2].

The key message is that priapism will not resolve on its own once it has lasted several hours. Do not wait to see if it goes away. The four-hour mark is the critical threshold: if your erection has lasted this long, go to your nearest accident and emergency department immediately, even if it is not painful. Early treatment protects your future erectile function.

What to Do If You Experience Prolonged Erection on Tadalafil

If you have an erection that lasts longer than four hours while taking tadalafil, treat it as a medical emergency and go to A&E or call 999 [1][2]. Do not feel embarrassed—priapism is a recognised medical condition, and healthcare professionals are trained to treat it discreetly and effectively. Delaying treatment can result in permanent damage to the penis and long-term erectile dysfunction.

While waiting for medical help, you can try simple self-care measures that may help in the early stages, though these are not a substitute for professional treatment. Some men find that gentle exercise, such as walking or climbing stairs, can encourage blood to drain from the penis. Applying a cold compress or ice pack wrapped in a towel to the inner thigh or perineum may also help, though do not apply ice directly to the penis. Urinating can sometimes relieve pressure, and staying hydrated is sensible.

Do not take another dose of tadalafil or any other ED medicine if you are experiencing priapism. Once you have been treated, your doctor will advise whether it is safe to use tadalafil again or whether you should switch to a different treatment. Always inform any future prescriber that you have had priapism, as this will influence which ED medicines are suitable for you.

Self-Care Tips to Reduce Risk

Although you cannot completely eliminate the risk of priapism, you can take steps to minimise it. Always use tadalafil exactly as prescribed—do not take more than the recommended dose or take it more frequently than once a day for on-demand treatment [4]. If you are on daily tadalafil (2.5 mg or 5 mg), take it at the same time each day and do not double up if you miss a dose.

Avoid combining tadalafil with recreational drugs, especially 'poppers', cocaine, or other substances that affect blood pressure or blood flow. Limit alcohol intake, as heavy drinking can worsen erectile dysfunction and increase the risk of side effects [1]. If you have any blood disorders, such as sickle cell disease, leukaemia, or multiple myeloma, make sure your prescriber is aware, as these conditions carry a higher baseline risk of priapism even without ED medicines [2][4].

Alternative ED Treatments If Tadalafil Priapism Is a Concern

If you have experienced priapism with tadalafil, or if you have risk factors that make your prescriber cautious about prescribing it, several alternative treatments are available. Other PDE5 inhibitors—sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra)—work in a similar way to tadalafil but have shorter durations of action, which may reduce the theoretical risk of prolonged erection [3][5][6]. Sildenafil lasts about four to six hours, vardenafil about four to five hours, and avanafil about six hours, compared with tadalafil's 36-hour window [4][6].

Your prescriber may suggest starting with a lower dose of a shorter-acting PDE5 inhibitor and monitoring your response. Sildenafil is available from £0.45 per tablet at Cured Pharmacy (£0.36 with first-order code Ednew), while vardenafil costs £16.95 (£13.56 with code Ednew) and Spedra (avanafil) is £20.95 (£16.76 with code Ednew). All require a prescription following an online consultation reviewed by a UK prescriber.

Non-oral options include Eroxon, a topical gel that works within 10 minutes and is available without prescription, and Vitaros (alprostadil cream) or Caverject (alprostadil injection), which are prescription-only and work by a different mechanism [7]. Your GP or a specialist can also explore vacuum erection devices, penile injections, or psychological therapies if tablets are not suitable. The key is to discuss your concerns openly with your prescriber so they can tailor a treatment plan that balances effectiveness with safety.

When to Seek Urgent Medical Help for Tadalafil Side Effects

Priapism is the most urgent side effect of tadalafil, but other serious reactions require immediate medical attention. If you experience sudden loss of vision in one or both eyes while taking tadalafil, stop the medicine and go to A&E or call 999 [4]. This could be a sign of non-arteritic anterior ischaemic optic neuropathy (NAION), a rare but serious condition that can cause permanent vision loss. Similarly, sudden hearing loss or ringing in the ears (tinnitus) has been reported with PDE5 inhibitors and warrants urgent assessment [4].

If you develop chest pain, dizziness, or nausea during or after sexual activity, stop what you are doing and seek medical help immediately, as this could indicate a heart problem [1][4]. Do not take any more tadalafil until a doctor has assessed you. If you have taken tadalafil and then experience a severe allergic reaction—such as swelling of the face, lips, tongue, or throat, difficulty breathing, or a widespread rash—call 999 straight away [4].

Less urgent but still important side effects include persistent headache, flushing, indigestion, back pain, or muscle aches, which are common with tadalafil and usually mild [4]. If these become troublesome or do not settle after a few doses, contact your prescriber to discuss adjusting your dose or switching to a different ED medicine. Never ignore symptoms that worry you—early advice can prevent complications and ensure you get the most suitable treatment for your needs.

Reporting Side Effects

If you experience any side effect with tadalafil, whether listed in the patient information leaflet or not, you can report it via the UK Yellow Card scheme at https://yellowcard.mhra.gov.uk or through the Yellow Card app [12]. Reporting helps regulators monitor the safety of medicines and can lead to important updates in prescribing guidance. You can also tell your prescriber or pharmacist, who can report it on your behalf and advise you on next steps.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 17 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 17 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 17 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 17 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 17 October 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 17 October 2026]
7. Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 17 October 2026]
8. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 17 October 2026]

Information on this page is for educational purposes only and is not medical advice. Prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting or changing any medication.