> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hi-doctor.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Caverject (alprostadil injection)

> How alprostadil injection works for erectile dysfunction, why the first dose is taught in clinic, and the priapism warning signs to know.

Alprostadil is a copy of prostaglandin E1, a substance the body makes
naturally that widens blood vessels. Caverject is the intracavernosal
injection form — it is not swallowed, but injected into the side of the
penis, so it acts on the blood vessels directly rather than circulating
through the whole body first.

## What it is

<CardGroup cols={2}>
  <Card title="Active ingredient" icon="flask">
    Alprostadil, chemically identical to prostaglandin E1.
  </Card>

  <Card title="Route" icon="syringe">
    Injection directly into the side of the penis (intracavernosal).
  </Card>
</CardGroup>

Caverject holds national authorisations rather than a centralised EU one; the
details on this page come from the Spanish authorisation (AEMPS registrations
60535 and 60911, holder Pfizer, S.L.), where both strengths are currently
marketed. In the United Kingdom, Pfizer Limited also holds a Caverject Dual
Chamber presentation at 10 and 20 micrograms. It has been authorised for use
in the EU since 29 November 1994, so a licensed doctor can prescribe it when
clinically appropriate.

<Note>
  Because it is injected, the first dose is normally given and taught in a
  clinical setting.
</Note>

## How it works

<CardGroup cols={3}>
  <Card title="A copy of prostaglandin E1" icon="flask">
    Alprostadil is placed into the penis itself, so it acts on the erectile
    tissue at the site rather than circulating through the whole body first.
  </Card>

  <Card title="Cavernosal muscle relaxes" icon="droplet">
    It relaxes the smooth muscle of the corpora cavernosa — the two spongy
    cylinders that run the length of the penis — and widens the cavernosal
    arteries feeding them. Blood flow into the erectile tissue rises, and
    that increase in flow produces rigidity.
  </Card>

  <Card title="It does not need arousal" icon="ban">
    Because it acts directly on the blood vessels, it does not depend on the
    signalling pathway used by PDE5 tablets such as sildenafil or tadalafil.
  </Card>
</CardGroup>

<CardGroup cols={3}>
  <Card title="A non-PDE5 route" icon="route">
    A different pathway from oral erectile dysfunction tablets.
  </Card>

  <Card title="Direct, local action" icon="crosshairs">
    Acts on the blood vessels at the site, not system-wide.
  </Card>

  <Card title="An option when tablets don't work" icon="circle-check">
    Considered when oral PDE5 tablets aren't the right fit or aren't allowed.
  </Card>
</CardGroup>

## What the studies reported

Efficacy and safety data for intracavernosal alprostadil were reported in
[N Engl J Med 1996](https://pubmed.ncbi.nlm.nih.gov/8596569/) (PMID 8596569),
including a six-month self-injection study. Every NCT identifier in
Hi-Doctor's evidence base links to its ClinicalTrials.gov record; a readout
is not the same as peer-reviewed publication.

## What has been reported

| Effect                                                             | Frequency reported                                                                                                                                                  |
| ------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Injection-site pain                                                | Very common in EU product information; mild penile pain occurred in 50% of men at some time in the six-month self-injection study, but after only 11% of injections |
| Prolonged erection (4–6 hours)                                     | 4% of patients per EU product information; 5% of men in the six-month self-injection study                                                                          |
| Priapism (erection lasting more than 6 hours)                      | 0.4% per EU product information; 1% of men in the six-month self-injection study                                                                                    |
| Penile fibrosis (angulation, fibrotic nodules, Peyronie's disease) | 3% of clinical-trial patients, rising to about 8% in an 18-month self-administration study                                                                          |
| Injection-site haematoma                                           | 3%                                                                                                                                                                  |
| Bruising                                                           | 2%                                                                                                                                                                  |

<Warning>
  An erection lasting 4 hours or more is priapism, and it is a medical
  emergency. Untreated priapism can permanently damage erectile tissue.
</Warning>

## Who it is not suitable for

A doctor assesses history and current medication before prescribing, and
decides whether Caverject or another sexual health option is appropriate.
Men with a history of priapism, Peyronie's disease, or who are taking
anticoagulants or antiplatelet medicines need a careful evaluation.
For men who prefer a cream applied to the tip of the penis rather than an
injection, [Vitaros](/library/medicines/vitaros) is the alprostadil cream
form, reviewed separately.

<Note>
  Because it is injected, the first dose is normally given and taught in a clinical setting. The reviewing doctor decides case by case — nothing here is prescribed without evaluation.
</Note>

## Common questions

<AccordionGroup>
  <Accordion title="How long does a Caverject injection last?">
    An erection typically lasts between 30 and 60 minutes. If it lasts 4 hours or more, seek urgent medical attention — untreated priapism can permanently damage erectile tissue.
  </Accordion>

  <Accordion title="Can I use Caverject if oral tablets have not worked for me?">
    Yes. Caverject acts through a different pathway from PDE5 inhibitor tablets such as sildenafil or tadalafil, so it is considered when oral tablets are not the right fit or are not allowed.
  </Accordion>

  <Accordion title="Does Caverject work without sexual arousal?">
    Because it acts directly on the blood vessels in the penis, it does not depend on the signalling pathway used by PDE5 tablets. It does not need arousal, but sexual stimulation naturally complements the effect.
  </Accordion>

  <Accordion title="What is the difference between Caverject and Vitaros?">
    Both contain alprostadil. Caverject is injected into the side of the penis (intracavernosal). Vitaros is a cream applied to the tip of the penis. Both act locally on the blood vessels rather than circulating through the whole body first.
  </Accordion>

  <Accordion title="How is Caverject prescribed through Hi-Doctor?">
    The questionnaire covers symptoms, cardiovascular history, current medication and allergies. A registered doctor reviews the case personally and decides whether Caverject or another option is appropriate.
  </Accordion>
</AccordionGroup>

## How Hi-Doctor handles it

The questionnaire covers symptoms, cardiovascular history, current
medication and allergies — see how [eligibility works](/essentials/how-it-works).
Certain answers, such as nitrate medication, rule treatment out entirely
because of a dangerous interaction; see [safety](/essentials/safety) for how
these checks run. Caverject is one of several [sexual health options](/essentials/treatments)
a doctor may consider. The consultation cost is set out on
[pricing](/essentials/pricing); the medicine itself is paid separately at a
pharmacy.

## Start a consultation

<Card title="Sexual health consultation" icon="stethoscope" href="https://hi-doctor.ai/consultation/sexual-health/1">
  Answer the sexual health questionnaire and a registered doctor reviews it.
  They decide whether treatment is appropriate, which one, and at what dose —
  and declining is a normal outcome. See [what it costs](/essentials/pricing)
  and [how the review works](/essentials/how-it-works).
</Card>

<Warning>
  This page is reference information, not medical advice and not a prescription.
  Whether a medicine is appropriate for you is decided by a registered doctor
  after reviewing your consultation.
</Warning>