A smooth-muscle relaxant injected to treat erectile dysfunction
Papaverine
A muscle-relaxing medicine used mainly as an injection into the penis to produce an erection in erectile dysfunction.
What is Papaverine?
Papaverine is a medicine that relaxes the smooth muscle in the walls of blood vessels, widening them and increasing blood flow. Its main modern use is as an injection into the penis to produce an erection in men with erectile dysfunction, and it has been used in the past to improve circulation. The most important risk is a prolonged, painful erection (priapism), which needs urgent medical help if it lasts too long, as it can cause lasting damage. It can also lower blood pressure and, less commonly, affect the liver, so it is used under specialist guidance with training in how to inject it.
Education and reference only. This is a plain-language guide to Papaverine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Papaverine is a smooth-muscle relaxant and vasodilator, which means it relaxes the muscle in the walls of blood vessels so they widen and let more blood flow through. Although it has been used in the past for circulation problems, its main use today is to treat erectile dysfunction: it is injected directly into the side of the penis to relax the blood vessels there and produce an erection. It is a specialist treatment, used after a man has been assessed and trained in how to use it safely. It is not a tablet for general use; the way it is given is an important part of how it works.
How it works
Papaverine works by relaxing the smooth muscle in blood vessel walls, which causes the vessels to widen so more blood can flow through them. When it is injected into the penis, this increased blood flow fills the spongy tissue and produces an erection, which is why it is used for erectile dysfunction that has not responded to other treatments. The same vessel-widening effect explains why it can lower blood pressure and cause flushing. Because it directly relaxes these vessels, the effect can sometimes be stronger or longer than wanted, which is the basis of its main risk, a prolonged erection.
Company & origin
Originated / developed by: Specialist manufacturers.
A medicine that relaxes the smooth muscle in blood vessel walls, used mainly as an injection into the penis to treat erectile dysfunction.
What it treats
Conditions Papaverine is used for
Practical use
How to take Papaverine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- When used for erectile dysfunction, it is injected into the side of the penis exactly as you have been trained by the specialist team.
- Never use more than the agreed amount or use it more often than advised.
- Seek urgent medical help if an erection lasts longer than the time you have been told (often about four hours).
- Tell the specialist team about other medicines you take, especially any that lower blood pressure or affect bleeding.
- Attend follow-up appointments so the team can check the technique is right and look for any problems.
Weighing it up
Advantages & disadvantages of Papaverine
Advantages
- An effective option for erectile dysfunction, including when tablets have not worked.
- Works directly where it is needed by widening the blood vessels in the penis.
- Can be self-administered at home once a man has been properly trained.
Disadvantages
- Can cause a prolonged, painful erection (priapism), which is a medical emergency.
- Has to be given by injection, which some people find off-putting.
- Can lower blood pressure and, with repeated use, cause scarring in the penis or, less commonly, affect the liver.
Practical use
Good to know
The single most important safety point with papaverine is the risk of a prolonged, painful erection, called priapism: if an erection lasts longer than the time you have been told (often around four hours), you must seek urgent medical help, because a long-lasting erection can permanently damage the penis. Men are carefully trained on the correct technique, how much to use, and how often it can be used, and are told never to use more than agreed. Because it widens blood vessels, it can cause flushing and lower blood pressure, which may make some people feel dizzy. Repeated injections can occasionally cause scarring or lumps in the penis over time, and it can sometimes affect the liver, so it is used under specialist supervision. It is not suitable for everyone, and a proper assessment is needed first.
Who should not take it / use with caution
- Men with conditions that make a prolonged erection more likely, such as sickle cell disease or certain blood disorders, should not normally use it.
- People who have had a serious allergic reaction to it should not use it.
- It is used with caution, or avoided, in people with liver problems or very low blood pressure.
- Men who cannot be relied on to seek help promptly for a prolonged erection are not suitable.
Monitoring
- Checking the injection technique and that the dose is right at follow-up.
- Watching for prolonged erections and any scarring or lumps in the penis over time.
- Reviewing liver blood tests and blood pressure where appropriate.
Side effects
- A prolonged, painful erection (priapism), which is the most serious risk and needs urgent help.
- Flushing, dizziness or low blood pressure from the widening of blood vessels.
- Pain, bruising or, with repeated injections, lumps or scarring at the injection site.
- Less commonly, changes in liver blood tests.
Key interactions
- Medicines that lower blood pressure can add to its blood-pressure-lowering effect.
- Blood-thinning medicines may increase the risk of bruising or bleeding at the injection site.
- Other treatments for erectile dysfunction should not be combined with it without specialist advice.
Available as: A solution for injection into the penis.
Answers
Papaverine: frequently asked questions
What is papaverine used for?
Its main use today is as an injection into the penis to produce an erection in men with erectile dysfunction; it has also been used in the past to improve circulation.
What is the most important risk?
A prolonged, painful erection called priapism; if an erection lasts longer than you have been told, often about four hours, you must seek urgent medical help to avoid lasting damage.
How is it given?
For erectile dysfunction it is injected into the side of the penis, using a technique you are carefully trained in by the specialist team.
Can it lower my blood pressure?
Yes, because it widens blood vessels it can cause flushing and lower blood pressure, which may make some people feel dizzy.
Can I use it as often as I like?
No. You must never use more than the agreed amount or use it more often than advised, as overuse increases the risk of a prolonged erection and other problems.
Authoritative sources
- BNF
- NICE CKS
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