Caverject Side Effects: What You Need to Know

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Key takeaways

• Caverject side effects include penile pain, bruising, and a risk of priapism (erection over 4 hours).
• Oral ED tablets are usually tried first as they are non-invasive and generally well tolerated.
• Caverject may suit men who haven't responded to tablets or cannot take PDE5 inhibitors.
• Seek urgent help if an erection lasts more than 4 hours or you have severe penile pain.
• Cured Pharmacy offers oral ED tablets from £0.45 after a UK prescriber consultation.

What is Caverject and how does it work?

Caverject is the brand name for alprostadil, a prescription medicine used to treat erectile dysfunction [7]. Unlike oral tablets such as sildenafil or tadalafil, Caverject is administered as an injection directly into the side of the penis (intracavernosal injection). The active ingredient, alprostadil, is a synthetic version of prostaglandin E1, a naturally occurring substance that relaxes smooth muscle and widens blood vessels in the penis.

When injected, alprostadil causes the blood vessels in the penis to dilate and the smooth muscle to relax, allowing blood to flow in and produce an erection [7]. Importantly, Caverject does not require sexual stimulation to work—the erection typically begins within 5 to 20 minutes of injection and can last for up to an hour. This is a key difference from PDE5 inhibitor tablets, which only work when you are sexually aroused.

Caverject is usually considered when oral ED tablets have not been effective, are unsuitable due to contraindications, or when a man prefers a treatment that does not depend on sexual stimulation. It requires training from a healthcare professional to ensure correct injection technique and dosing, and it is only available on prescription in the UK [7].

Common Caverject side effects you should know about

The most frequently reported caverject side effects relate to the injection site and the mechanism of action [7]. Penile pain is very common, affecting more than one in ten men who use Caverject. This pain can range from mild discomfort to more significant aching during or after the erection. Other common local reactions include bruising, bleeding at the injection site, and the formation of small lumps or nodules in the penile tissue (fibrosis), particularly with long-term use.

A serious but rare side effect is priapism—a prolonged, painful erection lasting more than four hours [7]. Priapism is a medical emergency because it can damage the penile tissue and lead to permanent erectile dysfunction if not treated promptly. Men using Caverject must be aware of this risk and seek urgent medical help if an erection lasts longer than four hours. Other less common side effects include dizziness, headache, and changes in blood pressure.

Because Caverject is injected directly into the penis, there is also a small risk of infection at the injection site if sterile technique is not followed. Some men may develop Peyronie's disease (curvature of the penis) with repeated use, though this is uncommon. It is essential to follow your prescriber's instructions carefully and attend follow-up appointments to monitor for any complications [7].

When to seek urgent help

If you experience an erection lasting more than four hours after using Caverject, go to A&E immediately or call 999 [7]. Do not wait to see if it resolves on its own. Other warning signs that require urgent medical attention include sudden severe pain in the penis, signs of infection such as redness, swelling, warmth or discharge at the injection site, or any sudden loss of vision or hearing. If you develop chest pain during sexual activity, stop and seek medical advice straight away.

Who might consider Caverject for erectile dysfunction?

Caverject is typically reserved for men who have not responded to oral PDE5 inhibitor tablets (such as sildenafil, tadalafil, vardenafil or avanafil) or for whom these tablets are not suitable [2][7]. It may also be an option for men who have erectile dysfunction caused by nerve damage, for example after prostate surgery or due to diabetes, where oral tablets are less effective.

Because Caverject works independently of sexual stimulation, it can be helpful for men with psychological or neurological causes of ED where arousal pathways are disrupted. However, the need for self-injection and the side-effect profile mean that many men prefer to try oral treatments first. Caverject requires manual dexterity and confidence to self-administer, so it may not suit everyone.

Men taking nitrates, nicorandil, or riociguat—who cannot use oral PDE5 inhibitors—may be able to use Caverject, as it works through a different mechanism and does not interact with these medicines in the same way [7]. However, a full medical assessment by a prescriber is essential to ensure Caverject is safe and appropriate. It is not suitable for men with certain penile abnormalities, bleeding disorders, or conditions that predispose to priapism, such as sickle cell disease or leukaemia [7].

How effective is Caverject compared to oral ED tablets?

Caverject can be highly effective, with clinical studies showing that around 70–80% of men achieve an erection sufficient for intercourse after injection [7]. This success rate is often higher than that seen with oral tablets in men who have not responded to PDE5 inhibitors, particularly in cases of severe ED or nerve damage. However, effectiveness must be balanced against convenience, side effects, and the invasiveness of the treatment.

Oral PDE5 inhibitors such as sildenafil (Viagra) and tadalafil (Cialis) are effective in approximately 60–70% of men with ED and are generally the first-line treatment because they are non-invasive, easy to use, and have a well-established safety profile [1][2][9]. Tablets require sexual stimulation to work, which many men find more natural, and side effects such as headache, flushing, and nasal congestion are usually mild and temporary.

The key advantage of Caverject is that it works regardless of arousal and can be effective when tablets have failed. The main disadvantages are the need for injection, the higher risk of penile pain and priapism, and the potential for long-term complications such as fibrosis. For most men, oral tablets remain the preferred option, but Caverject offers an important alternative when tablets are not suitable or effective [2][7].

Effectiveness in different causes of ED

Caverject may be particularly effective in men with ED caused by nerve damage, such as after radical prostatectomy or pelvic surgery, where oral tablets often have lower success rates [7]. It is also used in men with diabetes-related ED, where vascular and nerve damage can reduce the effectiveness of PDE5 inhibitors. In contrast, men with ED primarily due to psychological factors or mild vascular disease often respond well to oral tablets and may not need to consider injections [2].

Caverject side effects versus side effects of oral ED tablets

The side-effect profiles of Caverject and oral ED tablets differ significantly because of their different mechanisms and routes of administration. Caverject side effects are predominantly local, affecting the penis itself: pain, bruising, bleeding, nodules, and the risk of priapism [7]. These side effects are directly related to the injection and the local action of alprostadil in the penile tissue.

In contrast, oral PDE5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil) are taken by mouth and work throughout the body, so their side effects are more systemic [3][4][5][6]. Common side effects of oral tablets include headache, facial flushing, indigestion, nasal congestion, and sometimes visual disturbances such as a blue tinge to vision (particularly with sildenafil). These side effects are usually mild, short-lived, and related to the temporary widening of blood vessels.

Both Caverject and oral tablets can cause dizziness or low blood pressure, but this is more common with tablets, especially in men taking other blood-pressure medicines or alpha-blockers. Priapism is a risk with both types of treatment but is more common with Caverject [7]. Oral tablets carry a very small risk of sudden vision or hearing loss, which is not associated with Caverject. Overall, most men find the side effects of oral tablets easier to tolerate than the local pain and injection-related issues of Caverject, which is why tablets are usually tried first [2].

Alternatives to Caverject: oral tablets and other options

If you are concerned about caverject side effects or prefer a non-invasive treatment, oral PDE5 inhibitor tablets are the most widely used alternative [1][2]. Cured Pharmacy offers a range of licensed oral ED treatments, all available after an online consultation reviewed by a UK prescriber. Sildenafil (generic Viagra) starts from £0.45 per tablet (£0.36 with first-order code Ednew) and is taken about one hour before sex. Tadalafil (generic Cialis) is available from £7.95 (£6.36 with code Ednew) and can last up to 36 hours, offering more spontaneity.

Other oral options include vardenafil (generic Levitra) at £16.95 (£13.56 with code Ednew), which works in 25–60 minutes, and avanafil (Spedra) at £20.95 (£16.76 with code Ednew), which can work in as little as 15–30 minutes [6][11]. Branded Viagra and Cialis are also available for those who prefer the original formulations. All these tablets require sexual stimulation to work and are generally well tolerated, with mild, temporary side effects in most men.

For men who cannot take oral tablets or injections, other options include Vitaros, a prescription alprostadil cream applied to the tip of the penis, and Eroxon, an over-the-counter gel that works through a cooling and warming effect to stimulate blood flow [2]. Vacuum erection devices and penile implants are also available for more severe cases. If you are considering Caverject or any ED treatment, it is important to discuss all your options with a healthcare professional to find the most suitable and acceptable treatment for you.

NHS availability and private prescriptions

Caverject and other ED treatments are available on the NHS in certain circumstances, such as after prostate surgery, for men with diabetes, or for specific medical conditions causing ED [2]. However, NHS prescribing for ED is restricted, and many men obtain treatment privately. Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering private prescriptions for oral ED tablets after a consultation with a UK prescriber. This service is convenient, confidential, and allows you to access a wide range of treatments at transparent prices.

When to get urgent help

• Erection lasting more than 4 hours (priapism) – go to A&E or call 999 immediately
• Sudden severe pain in the penis or signs of infection (redness, swelling, discharge) at injection site
• Chest pain during or after sexual activity – stop and seek medical help
• Sudden loss of vision or hearing – seek urgent medical attention
• Severe dizziness, fainting, or difficulty breathing after using any ED treatment

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