1,600 people ask Google questions about Penile (Intracavernosal) Injections every month. This section gives you an overview — but this is the MOST IMPORTANT MESSAGE:

You MUST get tailored support and guidance. Get in-person training from a qualified specialist before doing penile injections.

1. Ask your GP/ Urologist for a referral to a Penile Injection Specialist.

2. If they do not have a referral pathway, contact one of our recommended Penile Injection Specialists. They have kindly contributed their knowledge and experience to this web page.

— Skip to Specialists List —

What is TriMix and how does it work?

Intracavernosal injections work by dilating blood vessels in the penis. This allows blood to flow through the cavernous tissue, thus leading to an erection.

The TriMix formula contains three ingredients (as the name suggests). However, different compounding pharmacies use different ingredients.

For example, Tim Stewart says that the TriMix they use at his pharmacy in Canberra contains Alprostadil, Phentolamine and Papaverine.

On the other hand, Melbourne based Urology Nurse, Emma Birch, uses a TriMix formula from Slades Pharmacy that does not include Alprostadil.

There is a potential benefit to this. Alprostadil is a Prostaglandin, which can cause a painful throbbing sensation: “So painful they can’t even have a sheet lie on top of the erection”, Emma says.

Therefore, if you are experiencing any throbbing or painful side effects from TriMix (or another injection formula), it is worth booking an appointment with an Injection Specialist to see if it contains Prostaglandin.

NOTE: Check with your pharmacist whether your injection formula needs to be kept in the fridge. TriMix traditionally needed to be refrigerated at all times, however some recent versions do not require that.

What is the typical dose of TriMix?

There is no ‘typical’ dose, it varies a lot between people. You will be instructed on how to safely increase the dosage to find what works best for you when receiving injection therapy training.

Emma Birch says it can be anywhere from 10 - 100 units, and there is also the option of double strength TriMix if that does not work.

Keep in mind, there are many different formulas besides TriMix (for example, Caverject, Quadmix and Promix). For any formula, you need to obtain a prescription from your Doctor or a Nurse Practitioner (this is a nurse who can prescribe, like Kath Schubach).

Penile Injection Instructions.

1. You draw air into the syringe (an insulin syringe is most commonly used), down to the amount that you're going to dose with - this isn't going to be a guessing game. The injection therapist will tell you the best amount to start with (see specialist list).

2. The needle goes through a rubber bung in the top of the vial. You'll insert some air (into the vial) just to equalize it a little bit. And then you'll draw down to the amount of liquid that you're going to inject.

3. It's important to hold the vial upright and upside down (when loading your syringe) because otherwise you may end up loading your syringe with air, and then injecting air into the penis. This isn't going to cause any problems, but it's not going to induce an erection.

4. Swab the area you will be injecting (see next step) with an alcohol swab first.

5. Next, you pull the foreskin down - if you've got one of course. Stretch the penis out away from your body. If you imagine the penis as a clock, you are injecting into either 10 o'clock or 2 o'clock.

6. Hold the syringe like a dart, and then put it straight in (watch the video above for idea on placement). You want to avoid any visible veins or arteries. If there are any, just inject a different spot.

7. Once the needle is in, push the plunger all the way down, then remove, and put straight in a sharps container.

8. Lastly, put a good amount of pressure onto the site you've just injected. Then start massaging quite firmly. This helps the blood flow and spread the medication throughout the penis.

What are the side effects of injecting?

Typically there are no systemic side effects because the drug is just being injected into the spot where we want it to work.

Generally the most common effect is a bit of pain in the penis. If the pain is more than just a bit, there are methods that you can use to circumvent this.

What can you do if injection-induced erections are painful?

This could be due to the formula, so it is best to book to see an injection specialist for their opinion.

On the other hand, it could also be that the penile tissue is simply getting used to being ‘stretched’ again. In the same way your muscles will ache if you haven’t exercised for a while, the penile tissue needs regular stretch and blood flow to stay in top condition.

How long does the erection last after injecting?

A typical erection after one of these injections lasts about an hour, and that is the time-frame we aim for with injection-induced erections. 

If the erection is lasting two hours, you can start to manually bring the erection down using methods to constrict the blood vessels. You can try Sudafed (pseudoephedrine) tablets (remember to ask your doctor or pharmacist about this first because these are not suitable for everyone). The guidelines for treating a prolonged injection recommend 120 milligrams, so for Sudafed you would take two tablets.

You can also jump in the shower. But you’ll have to experiment with temperature here as there are a couple of schools of thought over what is most effective. A hot shower follows the idea that vasodilation throughout the body will shunt blood away from the penis, but a cold shower follows the idea of vasoconstriction in the penis to make the erection subside.

Hopefully, these tips will do the trick and you won't need to do anything further.

However, if the erection is lasting longer, say four hours, then that is considered a medical emergency and you need to go to hospital. This is called a ‘Priapism’. It is very rare but possible and you need to know what to do if it happens.

How often can/should someone use Penile Injections?

It is not recommended to use penile injections more than twice a week (ref: Tim Stewart).

If you are using injections for penile rehabilitation purposes, it is recommended using injections once to twice a fortnight (ref: Tim Stewart).

This is because if you're injecting into the same area often, you can cause scarring in that area. It might even cause a bend in the penis, this is called Peyronie's Disease. We have a recorded webinar you can watch to learn more about this here.

We recommend alternating the injection site each time to prevent this (one side one week, then the other side the other week).

Can the needle cause damage to the penis?

So long as you are doing the injection process correctly, the needle will not damage the penis.

You might experience bruising to the site of injection, this is not uncommon, however it is not permanent or damaging. The bruising is caused by little capillaries bursting. Make sure you are alternating site of injection to avoid scarring.

Also, make sure the needle is not bent prior to injection. Always check beforehand that the needle is perfectly straight.

Can Viagra or Cialis be used with injections?

It is generally advised not to use Penile Injections and PDE5 Inhibitors (such as Viagra/Cialis) together. This would increase your risk of Priapism (prolonged erection), and can cause hypotension (blood pressure dropping too much).

However, if your prescribing Doctor recommends it for you then you should follow their guidelines. But in general do not take them together.

Do you need a script for injections?

Yes, you absolutely do.

However, keep in mind most GPs (in Australia) won’t have TriMix on their computer system - in fact you might have to educate them about penile injections. You could direct them here as a resource, and you may be better off asking your Urologist for a prescription and a referral to a Penile Injection Specialist for training.

What if injections aren’t working?

This could be due to either the technique, or the formula.

The dose range you can try with different injection formulas varies, and keep in mind there are many types of formulas you can try.

For example, Caverject can only go up to a 20mcg dose, but you can have TriMix made at a higher dose.

The technique is important too. Troubleshooting with a specialist is imperative if the injections aren’t working for you. There are many options out there to try. There’s no need to throw in the towel if they don’t work the first time, or stop working over time.

Is Caverject better than TriMix?

Caverject tends to be slightly more effective in terms of giving an erection, however, it can also cause pain due to the high level of Prostaglandin.

What is TriMix/Alprostadil Gel?

TriMix, or Alprostadil, gel delivers the erection-inducing formula, but through the urethra.

The gel comes in a prefilled syringe. You insert this into the urethra and it gets absorbed into the penis.

You first want to make sure you have emptied your bladder. Then, Tim Stewart advises using a vacuum device beforehand (5-10 minutes) to get a bit of stretch.

Once ready, hold the penis upright, pinch the head (glans). Take the cap off the urethral gel (1/2 ml) and insert the top of the syringe into the urethra.

The gel insertion needs to be done very slowly, over 20-30 seconds. Once finished, keep the penis upright for at least a minute afterwards, if it falls down the gel will fall out.

The insertion can be difficult so we recommend doing your first one with trained injection therapist.

The gel has a big advantage because there is no needle. However, it needs to be kept refrigerated so the insertion can be uncomfortable because it is cold.

Evidence suggests that TriMix gel works in 35-70% of patients with E.D. (ref: Tim Stewart). However, the success rate is much lower for men after Prostatectomy.

What is an Auto-injector?

With an auto-injector, you load the syringe into a device that automatically pushes the needle into the penis with a click of a button. This avoids seeing the needle, having to insert it or even having to push the plunger.

You can buy auto-injectors online. However, Emma Birch advises to always ask your injection specialist which one they recommend for you. This is because the device needs to be compatible with the syringe and specific formula you are using.

Do you have to use condoms with injections or urethral gel?

Most of the urethral gel will be absorbed and kept in the shaft of the penis, a small amount might come out, but it won’t cause any harm to your partner. If you find that a significant quantity comes out, then the technique might need adjusting.

With injections, there might be a small amount of blood that comes out of the injection site. This can increase risk of transmittable diseases so it is advisable to use condoms with new partners as part of safer sex practice.

PENILE INJECTIONS: SAFETY CHECKLIST

Kath Schubach gave us her top safety tips for men using penile injections.

1. Get the right assistance. Book in to see a specialist trained in giving injections to learn the technique. Kath: “Injections can be very good, but if you have a bad experience then you won't want to go down that pathway again.”

2. Get the appropriate dose for you. There are individual factors that affect dosage. As we mentioned above, you need to avoid Priapism (prolonged erections lasting over 4 hours).

3. Get the correct technique education. For example, you must only inject laterally along either side of the penis shaft, never on the top, or the bottom.

4. Follow up with your specialist. This process tends to require tweaking along the way to get the right dosage and formula. Kath offers patients whatever follow-up they require: “(the process) is usually a couple of visits. But if the patient needs more, then that's open to negotiation. It’s not a case of one appointment and then you're never seen again. It depends on what the patient requires.”

DISCLAIMER: This page is a short summary, it is not comprehensive, and only contains general information about medical conditions and treatments. The information is not medical advice, and should not be treated as such. If you have any specific questions about any medical condition you should consult your doctor or other professional healthcare provider. You should never delay seeking medical advice, disregard medical advice, or discontinue medical treatment because of information on this website.