Caverject or PDE-5-Inhibitors

Dr Kathryn Basford

Medically reviewed by

Dr Kathryn Basford

Last reviewed: 11 Jun 2019

Are injections better than pills for erectile dysfunction?


Are you looking to treat erectile dysfunction (ED), but would prefer something other than tablets like Viagra? Caverject is an injectable medicine that can reliably produce erections in 5 to 15 minutes without the need to take tablets.

Find out how Caverject works, where to get it, the risks, and how it compares to other options for treating ED.

How does Caverject compare to medications like Viagra?

Viagra is a medicine taken by mouth from a family of drugs known as PDE-5 inhibitors. The main difference between PDE-5 inhibitors and Caverject is that Caverject is normally only prescribed when other treatments have failed to work, or are not appropriate.

Caverject and PDE-5 inhibitors both work by increasing blood flow to the penis, but due to the direct way in which Caverject is used, there are some key differences:

How long does Caverject take to work?

5 to 15 minutes

How long does it last?

Depending on the dose, an erection will usually less than an hour.

Do I need to be sexually stimulated for it to work?


How often can you use it?

Daily, but not more than three times per week.

What if I have other conditions?

Caverject cannot be used in certain conditions affecting the blood, or if you have abnormalities of the penis.

How effective is it?

Around 94% of men report successful sexual activity after use.

Is it convenient?

The injections can be time-consuming or painful.

Caverject isn't the first choice – but, if you have tried PDE-5 inhibitors in the past and have not been satisfied with the results, Caverject may be a suitable alternative. Compared to PDE-5 inhibitors, Caverject can work faster and does not rely on the need to be sexually stimulated to have an erection.

Fewer whole-body effects – as the medication in Caverject is released directly into the penis, the chances of experiencing side-effects in other parts of your body is reduced. You may want to consider using Caverject as an alternative to PDE-5 inhibitors if you have experienced side-effects such like:

  • headaches
  • flushing
  • indigestion
  • nasal congestion
  • dizziness
  • abnormal vision
  • back pain
  • muscle pain

You may have been told that PDE-5 inhibitors are not suitable for you based on a medical condition you have. Depending on your situation, Caverject may be an alternative that could be safe to use.

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How does Caverject help erectile dysfunction?

The active ingredient in Caverject is alprostadil; it’s very similar to a natural hormone in your body that controls the blood vessels. For people with ED, it can make it easier to have an erection by widening the blood vessels and increasing blood flow to the penis, usually within five to fifteen minutes after use. Around 94% of men report successful sexual activity after using Caverject.

Where can you buy Caverject?

Caverject is a prescription-only medicine, but it’s not always available on the NHS. To buy it, you’ll usually need a private prescription. Your GP may be able to provide this for you, or you may need to see a specialist, for example a urologist.

Are there any risks to using Caverject?

Risks to using Caverject include:

  • poor injection technique
  • pain
  • scarring
  • bruising
  • colour change
  • rash
  • penile abnormalities, like Peyronie’s disease (scar tissue causing the penis to be bent when erect, not straight) or fibrosis
  • erections lasting too long or when not wanted (priapism)

If you’re considering using Caverject, bear in mind that using the syringe or injection device can be quite difficult – this is especially if you have problems with your hands or do not like needles. More people decide to stop using Caverject because of the technique than because of poor results. To make the process easier, it might be worth both you and your partner learning how to prepare and give the injection.

The most common side-effect of Caverject is pain in the penis after the injection – about 30% of people experience pain in their penis at least once after using Caverject. However, it’s described as mild or moderate pain in most cases, and only three out of every 100 people stop using the medicine because of the pain.

There’s also a risk of scarring, bruising, colour changes or rashes to the skin of the penis following an injection. It’s important to follow the instructions carefully to reduce the chances of this occurring.

Long-term use – using Caverject long-term is generally safe, but there’s a small risk that over time you could develop abnormalities in your penis that may mean you have to stop using it. Peyronie's disease or penile fibrosis are conditions where scar tissue in the penis can cause pain or bends in the penis. Caverject should not be used if you develop a problem like this.

Priapism – a risk shared by most medicines used to treat ED is having an unwanted erection that lasts a long time. With Caverject, 4% of people have reported having an erection that lasts for four to six hours. In most cases, the erection will go away by itself with less than 1% of people experiencing an erection that has lasted longer than six hours. This is an emergency and medical help should be sought immediately if this happens. The duration of the erection depends on the dose so your doctor will start you on a low dose to try to avoid this problem.

What alternatives to Caverject are there? (like PDE-5 inhibitors)

The main alternatives and first choice medications for erectile dysfunction are PDE-5 inhibitors:

  • Viagra (sildenafil) – was the first PDE-5 inhibitor on the market. Its effects start 30 to 60 minutes after taking the tablet but can be less effective if taken after a large meal. The effects can last for up to twelve hours with 60 to 80% of people experiencing improved erections during that time. Headache and flushing are the most common side-effects. You can get Viagra Connect over the counter
  • Cialis (tadalafil) – may start to work slightly faster than Viagra, after about 30 minutes. The effects tend to last longer than Viagra too, up to 36 hours, and aren’t affected by the food you eat. 70 to 80% of people taking Cialis experienced improved erections. Headache and indigestion are the most common side-effects. You can also get generic Tadalafil and Cialis Daily
  • Levitra (vardenafil) – is a slightly newer PDE-5 inhibitor than Viagra or Cialis. It works after around 30 minutes, but the tablet form can be affected by heavy meals. An orodispersable tablet version that dissolves on the tongue is available that isn’t affected by eating, and is good for people that find it hard to swallow tablets. 70 to 80% of people experienced improved erections. Headache, flushing and nasal congestion are the most common side-effects
  • Spedra (avanafil) – is one of the newest PDE-5 inhibitors. It can more precisely target the penis when it’s swallowed so there should be fewer side effects in other parts of the body. 60 to 70% of people taking Spedra have been able to have sex within 15 minutes of taking the medicine. Headache is less common than with the other PDE-5 inhibitors, but it’s still the most common side-effect of this medicine

There are some other treatment option available too:

  • Vacuum erection devices (penis pumps) – can be a suitable alternative for many people, especially those that cannot take medication for health reasons. The device is like a pump; it uses suction to keep blood in the penis and trigger an erection. While it can be very effective at producing an erection, some people have reported lower levels of satisfaction due to pain, numbness or not being able to ejaculate
  • Penile prosthesis – a device which is implanted into the penis. This method offers a permanent solution to ED without needing the continuous use of medicine. The device is an inflatable implant which can be manually switched on to produce an erection and then switched off again. You may want to consider an implant if all other methods haven’t worked for you. 90 to 100% of people are satisfied with the result
  • Lifestyle changes – if you are overweight then losing weight is known to help with ED. It can help to quit smoking or doing recreational drugs. If you drink alcohol, try cutting back to see if this helps. Stress is linked with ED, so changes to your lifestyle to bring your stress levels down may help. Regular exercise can help reduce stress, help with weight loss, and reduce ED
  • Controlling your other health conditions – ED is sometimes a symptom of another condition or a side-effect of a medicine. If you have a condition like diabetes, depression, high blood pressure or thyroid problems, talk to your doctor about your situation. By working together to control the condition, you may find that ED will improve. If you suspect that one of your medicines is causing the ED, your doctor may be able to switch it for something else
  • Psychosexual counselling – can help with erectile dysfunction and psychological therapy may be especially helpful if you have anxiety or depression, and this is something you can do alone or with your partner. Some people report getting help from acupuncture therapy, but there’s not much evidence that this works
  • Herbal remedies – these are not generally considered to be very effective. If you are thinking about using herbal medicine, make sure to buy one with a Traditional Herbal Registration number and speak to your doctor or pharmacist first
Medically reviewed by:
Dr Kathryn Basford Accreditations: MB, ChB, MPH

Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with ZAVA. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.

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Last reviewed: 11 Jun 2019

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ZAVA offers a convenient and discreet service to help men improve their erectile dysfunction. There are a number of treatments you can consider. Continue to our erectile dysfunction service page to learn about the treatment options available.

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