Prostaglandin injections offer an effective treatment for erectile dysfunction when oral medications have not worked or are unsuitable. This therapy involves injecting alprostadil directly into the penis to produce an erection within minutes. Administered under specialist guidance, intracavernosal injections represent a well-established second-line option recommended by NICE. Whilst the prospect of self-injection may seem daunting, comprehensive training and support from urology or sexual health clinics ensure patients can use this treatment safely and confidently at home. Understanding proper technique, safety precautions, and when to seek help is essential for successful outcomes.

What Is Prostaglandin Injection Therapy for Erectile Dysfunction?

Prostaglandin injection therapy, formally known as intracavernosal injection therapy, involves administering a medication directly into the corpus cavernosum of the penis to induce an erection. The most commonly used prostaglandin is alprostadil (prostaglandin E1), which works by relaxing smooth muscle tissue and dilating blood vessels within the penis, thereby increasing blood flow to produce an erection suitable for sexual intercourse.

This treatment is typically considered when oral phosphodiesterase-5 (PDE5) inhibitors such as sildenafil or tadalafil have proven ineffective or are contraindicated. According to NICE guidance, intracavernosal injections represent a second-line treatment option for erectile dysfunction. Alprostadil acts locally at the injection site, producing an erection within 5 to 20 minutes that typically lasts between 30 minutes and one hour. The medication bypasses the need for sexual stimulation to trigger the physiological cascade, making it effective even in cases where nerve pathways are compromised.

In the UK, MHRA-approved formulations include Caverject Dual Chamber and Viridal Duo, both single-use preparations that provide accurate dosing. Alprostadil is not suitable for everyone. You should not use this treatment if you have:

• Conditions that predispose to priapism (prolonged erection), such as sickle cell disease or trait, multiple myeloma, or leukaemia

• Penile deformity, Peyronie's disease, or a penile implant

• Anatomical abnormalities of the penis

• A history of priapism

• Increased bleeding risk, particularly if you are taking anticoagulants or antiplatelet medicines

Patients are initiated on this therapy under specialist supervision in urology or sexual health clinics, where healthcare professionals provide comprehensive training on injection technique, dose titration, and safety monitoring. Your first dose will be given in the clinic to establish the correct dose and ensure you can use the treatment safely. This supervised approach helps minimise the risk of complications such as priapism or penile fibrosis whilst optimising treatment outcomes.

Preparing for Your Prostaglandin Injection

Proper preparation is essential to ensure safe and effective administration of prostaglandin injections. Before your first self-administered injection, you will receive thorough training from a specialist nurse or urologist, including hands-on demonstration and supervised practice.

Storage requirements vary by product, so always follow the instructions in your Patient Information Leaflet. Caverject Dual Chamber is typically stored below 25°C and does not require refrigeration, whilst Viridal Duo must be refrigerated between 2°C and 8°C. Always check the expiry date and the strength of your dose before use. Do not use the medication if the solution appears cloudy, discoloured, or contains visible particles.

You will need:

• The prescribed alprostadil preparation (single-use vial or pre-filled device)

• Alcohol wipes for skin preparation

• A sharps disposal container

• Clean, dry hands and a private, comfortable space

Sharps containers are usually provided by your specialist clinic or can be obtained on prescription from your GP. Disposal arrangements vary locally—your clinic will advise you whether to return full containers to the pharmacy, clinic, or arrange council collection. Never dispose of needles in household waste.

Before injection, wash your hands thoroughly with soap and water, then dry them completely. If your medication has been refrigerated, you may remove it a few minutes beforehand, though this is not essential for the treatment to work. Use each needle and syringe only once—never share injection equipment.

Timing and frequency: Plan to inject when you anticipate sexual activity, as the erection will develop within 5 to 20 minutes. Do not inject more than once in a 24-hour period, and no more than three times per week, as recommended in the product information. This frequency limitation helps prevent complications such as penile scarring or fibrosis. Avoid injecting into areas of visible scarring, plaques, infection, or where you can see veins. Ensure you are in a relaxed state, as anxiety can affect the injection process and treatment response.

Step-by-Step Guide to Injecting Prostaglandin Safely

The injection technique requires precision and care to maximise effectiveness whilst minimising discomfort and complications. Always follow the specific instructions provided in your Patient Information Leaflet and the training you received from your specialist. The following steps provide general guidance:

Step 1: Identify the injection site. Hold the penis firmly and gently stretch it. The injection must be administered into the lateral aspect (side) of the mid-to-proximal shaft. Imagine the penis as a clock face viewed from above: inject at the 10 o'clock or 2 o'clock position. Avoid the top (12 o'clock, where veins are visible), the underside (6 o'clock, where the urethra runs), the head (glans), and any visible veins, scars, or plaques. Alternate between the left and right sides with each injection to prevent localised tissue damage, and rotate sites systematically.

Step 2: Clean the injection site. Using an alcohol wipe, cleanse the chosen area with a circular motion, working outward from the centre. Allow the skin to air-dry completely—this takes approximately 30 seconds and prevents stinging upon injection.

Step 3: Prepare the syringe. Follow the instructions in your Patient Information Leaflet to prepare your specific product. If drawing up from a vial, ensure no air bubbles remain. Hold the syringe like a pen, with the needle bevel facing upward.

Step 4: Insert the needle. Hold the penis firmly. Insert the needle perpendicular to the penile shaft (straight in, at a 90-degree angle) at your chosen site. Follow the depth guidance provided in your training and product leaflet. If you feel severe pain, significant resistance, or see brisk bleeding, stop and seek advice.

Step 5: Inject the medication. Depress the plunger slowly and steadily over 5 to 10 seconds. Rapid injection may cause discomfort.

Step 6: Withdraw and apply pressure. Remove the needle smoothly and immediately apply firm, continuous pressure to the injection site with an alcohol wipe or clean gauze for 2 to 5 minutes. This compression is essential to prevent bruising and helps distribute the medication. If you are taking anticoagulants or antiplatelet medicines, you may need to apply pressure for longer. Dispose of the needle immediately in your sharps container—never re-use needles.

Step 7: Gentle massage (if advised). If instructed during your training, gently roll or massage the shaft briefly to encourage even distribution of the medication throughout the erectile tissue. Follow the specific advice given for your product.

Managing Side Effects and When to Seek Medical Help

Whilst prostaglandin injections are generally well-tolerated, awareness of potential adverse effects and appropriate management strategies is essential for patient safety.

Common side effects include:

• Penile pain or aching (reported in 10–30% of users)—usually mild and resolves on its own. Over-the-counter paracetamol may provide relief if needed.

• Bruising or bleeding at the injection site—minimised by proper compression technique. If you are taking anticoagulants or antiplatelet medicines, you may bruise more easily; apply firm pressure for longer and inform your specialist if bruising becomes troublesome.

• Mild burning sensation—typically transient and may diminish with continued use.

These effects are generally manageable and do not require medical intervention unless they become severe or persistent.

Serious complications requiring urgent medical attention include:

Priapism—a prolonged, painful erection—represents a urological emergency. If your erection lasts longer than 2 hours, contact your specialist clinic or NHS 111 urgently for advice. If your erection is rigid and painful, or lasts 4 hours or longer, attend your nearest Emergency Department (A&E) immediately or call 999. Delayed treatment can cause permanent damage to the erectile tissue. Treatment typically involves aspiration of blood from the corpora cavernosa and possible injection of other medicines to reverse the erection.

Penile fibrosis or Peyronie's disease—repeated injections, particularly if administered incorrectly or too frequently, may cause scarring, lumps, or curvature of the penis. If you notice progressive penile deformity, hard lumps, or increasing curvature, contact your urologist for assessment.

Signs of infection—redness, warmth, swelling, pus, or discharge at injection sites warrant same-day GP review and possible antibiotic therapy. If you develop fever, severe pain, or feel unwell, seek urgent medical attention.

Dizziness or low blood pressure—though alprostadil acts locally, systemic absorption occasionally causes blood pressure reduction. If you experience significant dizziness or feel faint, lie down and contact NHS 111 for advice.

You should also contact your specialist if the treatment becomes consistently ineffective, as dose adjustment may be necessary, or if you develop anxiety about self-injection that affects your quality of life—psychological support or alternative treatments may be appropriate.

Reporting side effects: If you experience any side effects, talk to your doctor, pharmacist, or nurse. You can also report side effects directly via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. Reporting helps provide more information on the safety of medicines.

Effectiveness and What to Expect from Treatment

Intracavernosal alprostadil demonstrates high efficacy, with clinical studies reporting successful erections sufficient for intercourse in a substantial proportion of men, though individual response varies depending on the underlying cause of erectile dysfunction and other health factors.

Onset and duration of action are predictable. Most men achieve an erection within 5 to 20 minutes of injection, with the response typically lasting 30 to 60 minutes. The erection usually subsides naturally after ejaculation or within the expected timeframe. The duration is dose-dependent—your specialist will carefully adjust your dose during initial consultations to achieve an erection of appropriate duration whilst minimising the risk of priapism.

Dose optimisation is an individualised process. Initial doses are conservative (typically starting at 2.5 to 5 micrograms for Caverject), with gradual increases at subsequent appointments until an effective dose is established. The maximum dose varies by product: Caverject may be increased up to 60 micrograms, whilst Viridal Duo has a maximum of 40 micrograms per dose. Never adjust your dose without specialist guidance, as excessive dosing significantly increases the risk of priapism and other complications. Always use the dose and strength prescribed for you.

Long-term considerations include the potential for reduced efficacy over time in some men, necessitating dose adjustment. Some men discontinue treatment, most commonly due to needle anxiety, inconvenience, or relationship factors rather than treatment failure. However, many men continue successfully for years with maintained efficacy and satisfaction.

Alternative or additional options may be considered if alprostadil alone does not provide adequate response. In the UK, Invicorp (a combination of aviptadil and phentolamine) is a licensed alternative intracavernosal injection therapy that may be offered by specialists in certain circumstances. Additionally, prostaglandin therapy can be used alongside vacuum erection devices or as a treatment option whilst considering other interventions such as penile prosthesis surgery.

Regular follow-up with your specialist ensures ongoing safety monitoring, technique review, and opportunity to discuss concerns. The timing of follow-up appointments will be tailored to your individual needs. This collaborative approach optimises both clinical outcomes and quality of life, with studies demonstrating improvements in sexual confidence, relationship satisfaction, and overall psychological wellbeing among men successfully using intracavernosal therapy.

Frequently Asked Questions