For most men who require drug treatment for erectile dysfunction, oral medications such as Viagra (Sildenafil) or Cialis (Tadalafil) will be the preferred options.

In some cases though, these may not be suitable; and in others, men may try them but not find them to be effective. In such cases, an alternative treatment containing a different active ingredient, such as Caverject, may be recommended.

When considering ED medicines, Caverject on the surface may initially seem like a less appealing option than tablet treatments, because it has to be administered via an injection to the penis. However, while this may seem like a daunting process to those about to use it for the first time (and before you use it for the first time, a doctor or nurse will have to show you how to administer it) men usually tend to become well-accustomed to it after a couple of uses.

There are also other benefits to using Caverject when compared to different treatments. On this page, we’ll discuss these in more detail.


Oral tablet treatments for ED contain PDE5 inhibitors. These medicines are absorbed into the body in the stomach and then taken up into the bloodstream. As a result, they tend to take between 30 and 60 minutes to work. Spedra, the quickest oral tablet treatment for ED currently available, takes between 15-30 minutes to work.

Caverject is injected directly into the tissue in the shaft of the penis, and as such the drug doesn’t have to go through the process described above before becoming active. In many cases, the drug will produce a noticeable effect in 5-20 minutes.

This means that, on average, Caverject is likely to work more quickly than most oral tablets for erectile dysfunction.


In clinical trials published by manufacturers Pfizer, assessing the effectiveness of Caverject in men between the age of 23-69, 73% of men who self injected said that they had satisfactory intercours following administration; which would indicate a fairly high success rate on a par with median doses of PDE5 inhibitors.

The drug has a shorter half-life in the body than oral treatments. It will normally remain active in the body for no more than an hour (whereas tablets may last for up to five). However, this window should be long enough for the majority of men using it to have satisfactory intercourse.  

May be suitable for men who can’t take oral treatments

Using Caverject may not be quite as straightforward as taking a tablet, but it might be effective in men who have used oral treatments and found them to be ineffective. This makes it a useful backup option for men who have not responded to first line treatments.

It might also be considered where oral tablets are contraindicated or more likely to cause certain side effects. For example, someone with an allergy to one of the ingredients in a tablet may be more suited to Caverject.

Furthermore, because Caverject is administered locally, it doesn’t pass through the liver or kidneys to be metabolised like an oral medicine would; so people who have or have had liver or kidney problems in the past may be better suited to topical or localised treatment.

Side effects

Because they’re different medicines, the side effects associated with Caverject are different to those associated with PDE5 inhibitors such as Sildenafil.

At time of writing, the list of reported side effects in the patient information leaflet for Caverject was shorter than those in the Sildenafil leaflet. This may be because Sildenafil has been available for longer than Caverject, so the window for users to report side effects for Caverject has been shorter. (Obviously newer drugs start off with a comparatively small side effect profile which becomes more extensive the more people use it.)

It’s still important in any case to bear the side effects associated with Caverject in mind before use. If you develop a priapism for example, which is an erection that persists for four hours, you should seek medical attention immediately.

You can find more information on side effects in the patient information leaflet.

If you have any other questions about Caverject, or are wondering whether Caverject may be a more suitable treatment for you than an oral tablet, speak to your doctor.

Page last reviewed:  24/08/2018