Avanafil Priapism: How Common & What to Do

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Key takeaways

• Priapism with avanafil is very rare, affecting fewer than 1 in 1,000 men.
• Seek emergency help immediately if an erection lasts more than 4 hours.
• Never take more than the prescribed dose or combine avanafil with other ED medicines.
• Alternative treatments are available if priapism occurs or you're at higher risk.
• All prescription ED medicines require a UK prescriber consultation before supply.

How Common Is Avanafil Priapism?

Priapism is classified as a very rare side effect of avanafil, occurring in fewer than 1 in 1,000 men who take the medicine [6]. In clinical trials of avanafil, priapism was reported extremely infrequently, and most men using the medicine experience no serious adverse effects. Avanafil belongs to a class of medicines called PDE5 inhibitors, all of which carry a small risk of priapism, though the overall incidence remains very low across the entire class [6].

It's important to distinguish priapism from the intended effect of avanafil. The medicine is designed to help you achieve and maintain an erection during sexual activity, but that erection should subside naturally after intercourse or when sexual stimulation stops. Priapism, by contrast, is a persistent erection that continues for four hours or longer without sexual stimulation and is often painful [12]. If you experience an erection lasting more than four hours while taking avanafil, you must seek emergency medical attention immediately, as untreated priapism can cause permanent damage to the penis and long-term erectile dysfunction.

Certain factors may slightly increase the risk of priapism, including conditions that affect blood flow or blood cells, such as sickle cell disease, leukaemia, or multiple myeloma. Men with anatomical deformities of the penis may also be at higher risk [6]. Your prescriber will review your medical history during your online consultation to ensure avanafil is safe and appropriate for you.

Why Does Avanafil Cause Priapism?

Avanafil works by inhibiting an enzyme called phosphodiesterase type 5 (PDE5), which normally breaks down a chemical messenger that relaxes smooth muscle in the penis. By blocking PDE5, avanafil allows blood vessels in the penis to widen and fill with blood during sexual arousal, making it easier to achieve an erection [6]. In most cases, this effect is temporary and reverses naturally once the medicine wears off and sexual stimulation ends.

Priapism occurs when the normal mechanisms that regulate blood flow out of the penis fail, causing blood to become trapped in the erectile tissue. This can happen if the balance between blood inflow and outflow is disrupted for a prolonged period. While the exact reason why avanafil occasionally triggers priapism is not fully understood, it is thought to relate to excessive or prolonged relaxation of the smooth muscle, preventing the blood from draining away as it should [12].

The risk may be higher in men with underlying blood disorders or anatomical abnormalities, as these conditions can already predispose someone to abnormal blood flow in the penis. Taking more than the recommended dose of avanafil, or combining it with other medicines or substances that affect blood flow, may also increase the risk. Never take avanafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor, as these combinations can cause dangerous drops in blood pressure and other serious complications [6].

Other Medicines and Priapism Risk

Certain medicines can interact with avanafil and potentially increase the risk of side effects. Potent CYP3A4 inhibitors—such as ritonavil, cobicistat (found in some HIV medicines), ketoconazole, itraconazole, and clarithromycin—can raise avanafil levels in the blood, and avanafil is generally contraindicated or requires dose adjustment when used with these medicines [6]. Alpha-blockers used for prostate or blood pressure problems can also interact, causing dizziness or low blood pressure. Your prescriber will check all your current medicines during your consultation to ensure avanafil is safe for you.

At a glance

How Long Does Avanafil Priapism Last?

By definition, priapism is an erection that lasts longer than four hours. If left untreated, it can persist for many hours or even days, leading to permanent damage to the erectile tissue of the penis [12]. The longer priapism continues, the greater the risk of complications, including scarring, tissue death, and permanent erectile dysfunction. This is why immediate medical treatment is essential.

There are two main types of priapism: ischaemic (low-flow) and non-ischaemic (high-flow). Ischaemic priapism, the more common and serious form, occurs when blood cannot drain from the penis, causing oxygen deprivation to the tissue. This type is typically very painful and requires urgent treatment to restore blood flow and prevent lasting harm [12]. Non-ischaemic priapism, which is rarer and usually caused by injury, is less painful and may resolve on its own, but still requires medical assessment.

Avanafil-related priapism is most likely to be ischaemic. Treatment in hospital may include draining blood from the penis with a needle and syringe, injecting medicines to constrict blood vessels and reduce blood flow, or, in severe cases, surgery. The sooner treatment begins, the better the outcome. If you experience an erection lasting more than four hours, do not wait to see if it resolves on its own—go to A&E or call 999 immediately.

Self-Care Tips and What to Do If Avanafil Priapism Occurs

If you develop an erection that lasts longer than two hours while taking avanafil, try the following self-care measures while preparing to seek medical help: gently exercise by walking up and down stairs or doing light physical activity, as this may help redirect blood flow away from the penis. Applying a cold compress or ice pack wrapped in a towel to the inner thighs or lower abdomen may also help, though never apply ice directly to the penis itself. Urinating can sometimes help, as it may reduce pressure in the pelvic area.

However, these measures are not a substitute for medical treatment. If your erection persists beyond four hours, or if it is painful at any point, you must seek emergency medical attention immediately. Do not feel embarrassed—priapism is a recognised medical emergency, and healthcare professionals are trained to treat it promptly and discreetly [12]. Delaying treatment significantly increases the risk of permanent damage.

To reduce your risk of priapism in the first place, always take avanafil exactly as prescribed. The usual starting dose is 100 mg, taken about 15–30 minutes before sexual activity, with a maximum of one dose in 24 hours [6]. Do not take more than the recommended dose, and never combine avanafil with other ED medicines or recreational drugs such as poppers. Avoid heavy alcohol, as it can worsen side effects and reduce the effectiveness of the treatment. If you have any concerns about your dose or how to use avanafil safely, speak to your prescriber or pharmacist.

When to Stop Taking Avanafil

If you experience priapism, you should not take avanafil again until you have discussed the episode with a doctor. Priapism is a contraindication to further use of the same medicine, and your prescriber will need to review your treatment and consider alternative options [6]. Even if the priapism resolved quickly or with minimal intervention, the risk of recurrence may be higher, and a different approach to managing your erectile dysfunction will be necessary.

When to Seek Urgent Help for Avanafil Priapism

Priapism is a medical emergency. You should go to your nearest A&E department or call 999 if you have an erection that lasts longer than four hours, or if you have an erection that is painful and does not subside after sexual activity ends [6][12]. Do not wait overnight or try to manage it at home beyond the initial self-care steps described above. Prompt treatment is essential to prevent permanent damage to the erectile tissue and preserve your ability to have erections in the future.

Other serious side effects that require urgent medical attention include sudden loss of vision in one or both eyes, which may be a sign of a rare condition called non-arteritic anterior ischaemic optic neuropathy (NAION), and sudden decrease or loss of hearing, sometimes with ringing in the ears or dizziness [6]. If you experience chest pain, dizziness, or nausea during or after sexual activity, stop and seek medical help immediately, as these may be signs of a cardiovascular problem.

If you have any concerns about side effects or your response to avanafil, contact your prescriber, pharmacist, or GP for advice. You can also report side effects directly via the UK Yellow Card Scheme at https://yellowcard.mhra.gov.uk/. Reporting helps improve the safety information available for all patients.

Alternatives to Avanafil If Priapism Persists or You're at Higher Risk

If you have experienced priapism with avanafil, or if you have risk factors that make priapism more likely, your prescriber may recommend an alternative treatment for erectile dysfunction. Other PDE5 inhibitors—such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra)—also carry a small risk of priapism, so switching to another oral ED medicine may not eliminate the risk entirely [3][4][5]. However, some men tolerate one PDE5 inhibitor better than another, and your prescriber can help you find the most suitable option.

Non-oral treatments may be considered if oral medicines are not appropriate. Alprostadil, available as a urethral cream (Vitaros) or injection (Caverject), works by a different mechanism and may be an option for some men, though it also carries a risk of priapism and requires careful instruction and monitoring [7]. Vacuum erection devices and penile implants are non-drug alternatives that may be suitable for men who cannot use or do not respond to medicines.

Lifestyle changes can also play an important role in managing erectile dysfunction and may reduce your reliance on medication. Maintaining a healthy weight, exercising regularly, limiting alcohol, stopping smoking, and managing stress can all improve erectile function [1][2]. If your ED is linked to an underlying health condition such as diabetes, high blood pressure, or high cholesterol, treating that condition effectively can also help. Always discuss your full medical history and any concerns with your prescriber during your online consultation, which is reviewed by a UK-registered healthcare professional before any prescription medicine is supplied.

Cured Pharmacy's Approach to Safe ED Treatment

At Cured Pharmacy, every order for prescription ED treatment begins with a confidential online consultation. A UK-registered prescriber reviews your answers, checks for interactions and contraindications, and ensures the medicine is safe and appropriate for you. If avanafil is not suitable, or if you have concerns about priapism, your prescriber can recommend an alternative from our range of licensed ED treatments. You can also contact our pharmacy team at any time for advice and support.

When to get urgent help

• Erection lasting more than 4 hours, with or without pain
• Sudden loss of vision in one or both eyes
• Sudden decrease or loss of hearing, with or without ringing in the ears
• Chest pain, severe dizziness, or nausea during or after sexual activity
• Severe allergic reaction (swelling of face, lips, tongue, or throat, difficulty breathing)

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.