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Viridal (Alprostadil) Duo

Viridal (Alprostadil) Duo

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  • ✔️ Treats erectile dysfunction caused by neurogenic, vasculogenic, or psychogenic causes
  • ✔️ Produces erection within 5–20 minutes of intracavernosal injection
  • ✔️ Effective for men who cannot use oral PDE5 inhibitors
  • ✔️ Dual-chamber auto-injector pen for accurate, consistent dosing
  • ✔️ Clinically established alprostadil treatment with decades of evidence

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What Is Viridal Duo Injection and How Does It Treat Erectile Dysfunction?

 

Erectile dysfunction (ED) affects millions of men in the UK, and for many, oral tablets simply don't work well enough — or aren't suitable at all. That's where the Viridal Duo injection comes in. It's a clinically established intracavernosal treatment containing alprostadil, a synthetic form of prostaglandin E1, used to produce an erection directly by acting on the blood vessels of the penis. Available from Cured Pharmacy with a valid prescription, it offers a reliable option for men who haven't responded to first-line oral therapies.

Viridal Duo is supplied as a dual-chamber cartridge within a reusable auto-injector pen. The two chambers — one containing alprostadil powder and one containing solvent — are mixed immediately before use. This design helps maintain the stability of the active ingredient right up until the moment of injection. If you're exploring your options for managing ED, you might also find it helpful to browse our men's health range for complementary products and information.

 

How Does Viridal Duo Work to Produce an Erection?

 

Alprostadil works by binding to specific receptors in the smooth muscle cells of the penile arteries and corpus cavernosum. This triggers a cascade that raises intracellular cyclic AMP levels, causing smooth muscle relaxation and arterial dilation. Blood flows into the erectile tissue, and an erection follows — typically within 5 to 20 minutes of injection.

  • Alprostadil mimics naturally occurring prostaglandin E1
  • Smooth muscle in the penile arteries relaxes, widening blood vessels
  • Increased blood flow fills the corpus cavernosum
  • An erection is produced without requiring sexual stimulation to initiate it

Because it acts locally rather than systemically, Viridal Duo tends to have fewer cardiovascular side effects than some oral ED medications — though it still carries its own risk profile that you should discuss with your prescriber.

 

Who Is Viridal Duo Suitable For?

 

Viridal Duo is licensed for adult men with erectile dysfunction of neurogenic, vasculogenic, psychogenic, or mixed aetiology. It's particularly useful for men who cannot take PDE5 inhibitors (such as sildenafil or tadalafil) due to contraindications or lack of response.

  • Men with ED caused by nerve damage (e.g. following prostate surgery or spinal injury)
  • Men with vascular causes of ED who haven't responded to oral treatments
  • Men for whom PDE5 inhibitors are contraindicated (e.g. those taking nitrates)
  • Men with psychogenic ED who prefer a reliable, physically-initiated response

It is not suitable for men with conditions that predispose them to priapism (such as sickle cell anaemia or leukaemia), those with penile implants, or those with known hypersensitivity to alprostadil.

 

How Does Viridal Duo Compare to Other Alprostadil Treatments?

 

Feature Viridal Duo (Alprostadil Injection) MUSE (Alprostadil Urethral Suppository)
Route of administration Intracavernosal injection Intraurethral suppository
Onset of action 5–20 minutes 5–10 minutes
Efficacy in severe ED Higher — direct tissue delivery Lower — systemic absorption variable
Common side effects Penile pain, bruising at injection site Urethral burning, hypotension

 

How Should Viridal Duo Be Stored and Handled?

 

Proper storage is essential to maintain the integrity of the alprostadil. Viridal Duo should be stored below 25°C, away from direct light, and must not be frozen. Once the cartridge has been mixed (i.e. the two chambers combined), it should be used immediately and any unused solution discarded. Do not use the product past its expiry date.

The auto-injector pen itself is reusable, but cartridges are single-use only. Always dispose of used needles safely in an approved sharps container. If you have any concerns about handling the device, your GP, nurse, or pharmacist can provide a demonstration. For general health support products, our first aid collection includes sharps disposal and wound care essentials.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

Viridal Duo (Alprostadil) specifications
Treatment category Erectile dysfunction
Active ingredient Alprostadil
Mechanism of action Prostaglandin E1 receptor agonist — smooth muscle relaxation, vasodilation
Route of administration Intracavernosal injection
Strengths available 10 micrograms, 20 micrograms, 40 micrograms
Pack sizes 2-cartridge and 6-cartridge packs
UK classification Prescription Only Medicine (POM)
Drug class Prostaglandin / vasoactive agent
Preparation Powder and solvent for solution for injection (dual-chamber cartridge)
Suitable for Adult men with erectile dysfunction
Effective Within 5–20 minutes of injection

Specifications of Viridal Duo (Alprostadil)

 

What Is Viridal Duo and What Is It Used For?

 

Viridal Duo is a prescription-only medicine containing alprostadil — a synthetic prostaglandin E1 — used to treat erectile dysfunction (ED) in adult men. It is administered by injection directly into the erectile tissue of the penis (intracavernosal injection), producing an erection by increasing local blood flow. It is indicated when oral ED treatments have failed or are contraindicated. The NHS recognises alprostadil as a clinically effective treatment for ED across a range of underlying causes.

 

What Do You Need to Know Before Using Viridal Duo?

 

Before using Viridal Duo, your prescriber will review your full medical history. There are several important contraindications and warnings to be aware of:

  • Do not use if you have a known hypersensitivity to alprostadil or any excipient
  • Do not use if you have conditions predisposing you to priapism — including sickle cell anaemia, multiple myeloma, or leukaemia
  • Do not use if you have a penile implant (prosthesis)
  • Do not use if your partner is pregnant unless a condom is used, as alprostadil may affect foetal circulation
  • Use with caution if you have bleeding disorders or are taking anticoagulants
  • Not suitable for men with anatomical deformities of the penis (e.g. severe Peyronie's disease) unless assessed by a specialist

The following medicines may interact with Viridal Duo:

  • Antihypertensive agents — may enhance blood pressure-lowering effects
  • Anticoagulants (e.g. warfarin) — increased risk of bruising or haematoma at injection site
  • Other vasoactive agents used for ED — do not combine without specialist advice
  • Sympathomimetics — may reduce the efficacy of alprostadil

 

How Should You Use Viridal Duo?

 

Your doctor or specialist nurse will train you to self-administer Viridal Duo before you use it at home. Never attempt to inject without proper instruction. The injection is given into the lateral (side) aspect of the penis — never into a vein, the urethra, or the top or underside of the penis.

  1. Wash your hands thoroughly with soap and water
  2. Attach a new needle to the auto-injector pen
  3. Activate the dual-chamber cartridge by turning the mixing mechanism as instructed
  4. Gently roll the pen to mix the powder and solvent — do not shake
  5. Set the prescribed dose on the pen dial
  6. Clean the injection site on the lateral shaft of the penis with an alcohol swab and allow to dry
  7. Inject at a 90-degree angle into the corpus cavernosum
  8. Apply gentle pressure to the site for 1–2 minutes after withdrawal
  9. Dispose of the needle immediately in a sharps container
Indication Age Group Starting Dose Maximum Dose
Erectile dysfunction (neurogenic cause) Adult men 1.25 micrograms 20 micrograms
Erectile dysfunction (vasculogenic/psychogenic/mixed) Adult men 2.5 micrograms 40 micrograms

Do not use more than once in 24 hours, and no more than three times per week. Dose titration must be carried out under medical supervision.

 

What Are the Possible Side Effects of Viridal Duo?

 

Like all medicines, Viridal Duo can cause side effects, though not everyone experiences them. If you're managing any discomfort alongside your treatment, our pain relief collection may offer supportive options — though always speak to your pharmacist first.

Common side effects (may affect more than 1 in 10 users):

  • Penile pain or aching during or after erection
  • Prolonged erection beyond the desired duration
  • Haematoma or bruising at the injection site
  • Penile fibrosis or nodules with long-term use

Less common side effects (may affect up to 1 in 10 users):

  • Hypotension (low blood pressure) — particularly dizziness on standing
  • Urethral burning or discomfort
  • Testicular pain
  • Rash or skin irritation at the injection site
  • Headache

Serious side effect — priapism: If your erection lasts longer than 4 hours, go to your nearest A&E immediately. Priapism is a medical emergency. Delayed treatment can cause permanent damage to erectile tissue.

 

How Should You Store Viridal Duo?

 

Correct storage protects the stability of alprostadil and ensures the medicine works as intended. For broader health product storage guidance, our condoms and sexual health section also includes products that benefit from careful storage away from heat and light.

  • Store below 25°C — do not refrigerate or freeze
  • Keep in the original packaging to protect from light
  • Once the cartridge chambers are mixed, use immediately and discard any remainder
  • Keep out of the sight and reach of children
  • Do not use after the expiry date printed on the label
  • Dispose of used needles in an approved sharps container — never in household waste

Written and reviewed by our qualified team

Your safety and success are our highest priorities. Our medical team rigorously evaluates every product and piece of advice we provide, ensuring you receive only the most effective, science-backed solutions available.

Frequently Asked Questions

Where can I buy Viridal Duo injection online in the UK?

You can buy Viridal Duo injection online in the UK through Cured Pharmacy, a GPhC-registered online pharmacy. A valid prescription is required before dispensing, and our clinical team can guide you through the process safely and discreetly. Browse our men's health section for further information on related products.

How does Viridal Duo work in the body?

Viridal Duo contains alprostadil, a prostaglandin E1 analogue that relaxes smooth muscle in the penile arteries and corpus cavernosum, increasing blood flow and producing an erection. It acts locally at the injection site rather than systemically, which means it doesn't rely on the same pathway as oral PDE5 inhibitors. An erection typically occurs within 5 to 20 minutes of injection.

How do I use Viridal Duo step by step?

Viridal Duo is injected into the lateral shaft of the penis using the supplied auto-injector pen after mixing the dual-chamber cartridge. Your doctor or specialist nurse must demonstrate the correct technique before you self-administer at home. Never inject into a vein, the urethra, or the top or underside of the penis.

What is the correct starting dose of Viridal Duo?

The starting dose for most men with vasculogenic, psychogenic, or mixed ED is 2.5 micrograms, while men with neurogenic ED typically begin at 1.25 micrograms. Dose titration is carried out under medical supervision to find the lowest effective dose for you. The maximum dose is 40 micrograms per injection.

When is the best time to use Viridal Duo?

Viridal Duo should be injected approximately 5 to 20 minutes before you intend to have sexual intercourse, as this is when the erection typically develops. It can be used at any time of day, but should not be used more than once in any 24-hour period. Planning ahead is important, as the cartridge must be mixed immediately before use.

What are the most common side effects of Viridal Duo?

The most frequently reported side effect is penile pain or aching, which occurs in a significant proportion of users but is usually mild and short-lived. Bruising or haematoma at the injection site can also occur, particularly if the injection technique is not correct. If you experience a prolonged erection lasting more than 4 hours, seek emergency medical attention immediately.

What should I do if my erection lasts more than 4 hours after using Viridal Duo?

An erection lasting more than 4 hours is called priapism and is a medical emergency — go to your nearest A&E department immediately. Delayed treatment can cause permanent damage to the erectile tissue of the penis. Do not wait to see if it resolves on its own.

Who is eligible to use Viridal Duo?

Viridal Duo is suitable for adult men with erectile dysfunction of neurogenic, vasculogenic, psychogenic, or mixed origin who have been assessed by a doctor. It is particularly useful for men who cannot take oral PDE5 inhibitors due to contraindications or lack of response. Men with sickle cell disease, penile implants, or hypersensitivity to alprostadil should not use this product.

Can I use Viridal Duo if I take blood pressure medication?

Alprostadil can enhance the blood pressure-lowering effects of antihypertensive medicines, potentially causing dizziness or fainting. You should always inform your prescriber of all medicines you are taking before starting Viridal Duo. Your doctor may adjust your dose or monitor you more closely if you are on antihypertensives.

How often can I use Viridal Duo?

Viridal Duo should not be used more than once in any 24-hour period, and no more than three times per week. Exceeding this frequency increases the risk of penile fibrosis and other complications. Always follow the dosing schedule agreed with your prescriber.

What are the alternatives to Viridal Duo for erectile dysfunction?

Alternatives include oral PDE5 inhibitors such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra), which are often tried first. MUSE — an alprostadil urethral suppository — is another option for men who prefer to avoid injections. Your doctor can help you weigh up the options based on your medical history and preferences.

How long can I keep using Viridal Duo?

Viridal Duo can be used long-term, but regular follow-up appointments with your doctor are recommended to monitor for complications such as penile fibrosis or changes in erectile tissue. Long-term use should always be under ongoing medical supervision. If you notice any lumps, curvature, or persistent pain in the penis, report this to your doctor promptly.

Does Viridal Duo require sexual stimulation to work?

Unlike oral ED medications, Viridal Duo does not require sexual stimulation to produce an erection — the erection is a direct pharmacological response to the alprostadil injection. This can be an advantage for men with neurogenic ED where the nerve signals needed for arousal-induced erection are impaired. However, sexual stimulation may help maintain the erection once it has developed.

What happens if I miss a dose or forget to use Viridal Duo?

Viridal Duo is used on an as-needed basis rather than on a fixed daily schedule, so there is no concept of a "missed dose" in the traditional sense. Simply use it the next time you intend to have sexual intercourse, following your prescribed dose. Never use two doses within 24 hours to compensate.

What does the latest research say about alprostadil injections for ED?

Alprostadil intracavernosal injection has been used clinically for decades and remains one of the most effective treatments for ED, particularly in men who do not respond to oral therapies. Published clinical literature consistently demonstrates high rates of successful erections across a range of ED aetiologies. For broader sexual health support, explore our condoms and sexual health collection.

How Should You Use Viridal Duo?

Viridal Duo must only be used after you have been trained by a doctor or specialist nurse in the correct injection technique. The injection is given into the lateral (side) shaft of the penis — never into a vein, the urethra, or the top or underside of the penis. Always use a new needle for each injection and dispose of it safely in a sharps container immediately after use.

Follow these steps each time you use Viridal Duo:

What Is the Correct Dose of Viridal Duo?

The correct dose of Viridal Duo varies depending on the underlying cause of your erectile dysfunction and your individual response. Dose titration must always be carried out under medical supervision — never increase your dose without speaking to your prescriber first. The goal is to find the lowest dose that produces a satisfactory erection lasting no more than one hour.

When Is the Best Time to Use Viridal Duo?

Viridal Duo should be injected approximately 5 to 20 minutes before you intend to have sexual intercourse, as this is the typical window for the erection to develop. It can be used at any time of day, but planning ahead is important because the cartridge must be mixed immediately before injection and cannot be prepared in advance. Avoid using it more than once within any 24-hour period, regardless of timing.

Do not use Viridal Duo on two consecutive days. Spacing injections appropriately reduces the risk of penile fibrosis and other complications associated with frequent use.

How Long Can You Use Viridal Duo For?

Viridal Duo can be used on a long-term basis, but only under ongoing medical supervision. Your doctor will schedule regular follow-up appointments to check for signs of penile fibrosis, changes in penile anatomy, or other complications. If you notice any lumps, curvature, or persistent pain in the penis, stop using the product and contact your doctor promptly.

There is no fixed maximum duration of treatment, but the frequency limit of three injections per week must always be observed. Long-term users should have their treatment reviewed at least annually.

Do not exceed the recommended dose. If in doubt, speak to your pharmacist.

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What Are the Most Common Side Effects of Viridal Duo?

The most frequently reported side effect of Viridal Duo is penile pain or aching, which can occur during or after the erection. This is usually mild to moderate in intensity and tends to diminish with continued use as you become more accustomed to the injection. Bruising or haematoma at the injection site is also common, particularly if the technique is not quite right — your nurse or doctor can help you refine your approach.

  • Penile pain or aching (during or after erection)
  • Bruising or haematoma at the injection site
  • Prolonged erection beyond the desired duration
  • Minor bleeding at the injection site

What Are the Less Common Side Effects of Viridal Duo?

Less common side effects affect a smaller proportion of users but are still worth knowing about. Dizziness or light-headedness can occur due to a mild drop in blood pressure, particularly if you stand up quickly after the injection. Penile fibrosis — the development of scar tissue or nodules within the penis — can develop with long-term or frequent use and should be reported to your doctor.

  • Hypotension (low blood pressure) — dizziness or light-headedness
  • Penile fibrosis or nodules (with long-term use)
  • Testicular pain or discomfort
  • Urethral burning or irritation
  • Headache
  • Skin rash or irritation at the injection site

What Are the Serious Side Effects of Viridal Duo?

The most serious side effect of Viridal Duo is priapism — a prolonged, painful erection lasting more than 4 hours that is unrelated to sexual stimulation. This is a medical emergency. If left untreated, priapism can cause permanent damage to the erectile tissue of the penis, potentially resulting in long-term or irreversible erectile dysfunction. Go to your nearest A&E department immediately if this occurs — do not wait.

Severe allergic reactions (anaphylaxis) are rare but possible. Symptoms include swelling of the face, lips, or throat, difficulty breathing, or a sudden drop in blood pressure. Call 999 immediately if you experience these symptoms.

What Should You Do If You Experience Side Effects of Viridal Duo?

For mild side effects such as penile pain or minor bruising, these often resolve on their own and do not usually require you to stop treatment. Applying gentle pressure to the injection site for 1–2 minutes after withdrawal can help minimise bruising. If side effects are persistent, worsening, or causing significant distress, contact your prescriber or pharmacist for advice.

You can also report side effects directly to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. This helps regulators monitor the safety of medicines in real-world use.

Can Viridal Duo Interact With Other Medicines?

Yes — Viridal Duo can interact with several types of medication. Antihypertensive drugs may enhance the blood pressure-lowering effect of alprostadil, increasing the risk of dizziness or fainting. Anticoagulants such as warfarin may increase the risk of bruising or haematoma at the injection site. You should never combine Viridal Duo with other vasoactive agents used for erectile dysfunction without specialist advice, as this significantly increases the risk of priapism and cardiovascular effects.

Always give your prescriber and pharmacist a full list of all medicines, supplements, and herbal products you are taking before starting treatment with Viridal Duo.

If you are concerned about any side effects, contact your pharmacist or GP immediately.

Frequently Asked Question

Viridal Duo contains an active ingredient called Alprostadil, which is a type of vasodilator – a medicine that opens up blood vessels for increased supply of blood. 

The drug comes in a two-chamber glass cartridge, which consists of Alprostadil in one chamber and a sodium chloride solution in the other. 

When these compartments are mixed, they form an injectable solution, which creates a ready-to-use injection that is intended for intracavernosal application.

Viridal Duo works by increasing blood flow to the penis. 

The active Ingredient — Alprostadil. This relaxes the blood vessels in your penis, allowing more blood to flow into your penis, making it easier for you to get an erection.

An erection typically occurs 10-15 minutes after you inject Viridal Duo. 

The duration of effects generally lasts for an hour, but also depends on how the patient responds to it. 

No — unlike oral tablets such as Viagra or Cialis, Viridal Duo does not require sexual stimulation to produce an erection.
You should not use Viridal Duo more than once in 24 hours or more than 2–3 times per week. Overuse can cause prolonged erections or other side effects.
Some men experience a mild sting or ache at the injection site, especially during the first few uses.

Patient Information Leaflet

Important - Before taking any medication, it is always important to read the Patient Information Leaflet (PIL)

Written and reviewed by our qualified team

GPhC Number: 2233073
Tarun Kumar

Reviewed by:

Tarun Kumar

Superintendent/ Clinical Lead

📖 Find out more about our team of medical content authors and how we ensure the accuracy of our content with our content guidelines.

Content last updated: 31 Mar 2025

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What exactly is Viridal Duo used for?

Viridal Duo contains an active ingredient called Alprostadil, which is a type of vasodilator – a medicine that opens up blood vessels for increased supply of blood. 

The drug comes in a two-chamber glass cartridge, which consists of Alprostadil in one chamber and a sodium chloride solution in the other. 

When these compartments are mixed, they form an injectable solution, which creates a ready-to-use injection that is intended for intracavernosal application.

How does Viridal Duo actually work?

Viridal Duo works by increasing blood flow to the penis. 

The active Ingredient — Alprostadil. This relaxes the blood vessels in your penis, allowing more blood to flow into your penis, making it easier for you to get an erection.

How long does Viridal Duo take to work?

An erection typically occurs 10-15 minutes after you inject Viridal Duo. 

How Long Does Viridal Duo Last? 

The duration of effects generally lasts for an hour, but also depends on how the patient responds to it. 

Does Viridal Duo require sexual stimulation? No — unlike oral tablets such as Viagra or Cialis, Viridal Duo does not require sexual stimulation to produce an erection. How often can I use Viridal Duo You should not use Viridal Duo more than once in 24 hours or more than 2–3 times per week. Overuse can cause prolonged erections or other side effects. Is it painful to inject Viridal Duo? Some men experience a mild sting or ache at the injection site, especially during the first few uses.