Here’s our FAQ guide to Penile (Intracavernosal) Injections. This guide has been created from a mix of in-depth conversations with Penile Injection Specialists, feedback from men in our audience, and findings from clinical studies.

If you take away just one message, let it be this:

We’ve noticed that the BEST outcomes happen when men get tailored support and ongoing guidance from a qualified penile injection specialist. Here’s how to find one:

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.

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What is TriMix and how does it work?

All Intracavernosal injections (like TriMix) work in the same way: 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, be aware that different compounding pharmacies use different ingredients for Trimix!

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

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

Now, there is a potential benefit to this from Slades.

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’s worth checking if that formula 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?

It might surprise you to know that’s no ‘typical’ dose. It varies person to person.

You will be instructed on how to safely increase the dosage to find what works best for you when receiving injection therapy training from a specialist.

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 other 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).

What are the instructions for penile injections?

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 at 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. Don’t worry, this isn't going to cause any problems if it happens, but it's not going to induce an erection.

4. Next, 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.

5. Swab the area you will be injecting with an alcohol swab first.

6. Hold the syringe like a dart, and then put it straight in. You must only inject laterally along either side of the penis shaft, never on the top, or the bottom. 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 down, then remove the needle and put it 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.

How long does the erection last after injecting?

A typical erection after one of these injections lasts about an hour, and that’s the timeframe to aim for with injection-induced erections. 

If the erection lasts 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.

What are the side effects of injecting?

Typically there are no systemic side effects because the drug is just being injected into the one 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 - see the next question!

Is there a risk of fibrosis, Peyronie's, or scar tissue?

We posed this question to Melissa Hadley Barrett in a recent interview. She has not seen patients develop Peyronie’s because of injections, but she has seen a lot of patients develop Peyronie’s post-prostate cancer treatment (and some happen to have been using injections).

Her tips to avoid scar tissue are to change the spot you are injecting into each time. Using an auto-injector can also aid in reducing damage to the tissue. And aftercare for your penis is extremely important. This includes:

• Regular pump usage.

• Massaging Vitamin E oil/cream into the penis.

• Taking any required medications.

What’s a penile-injection-induced erection like?

It’s much more like a natural erection, so it should be warm and pink. When you're using a pump, it's pumping in more venous blood and when you use an injection it's pumping in more arterial blood, so the results post-injection tend to be much more natural feeling and looking than a pumped-erection.

The injection is also vasodilating the tissues in the penis, so you will have a constant blood flow (so the penis stays pink and warm to the touch throughout).

When you use an injection the whole shaft, even the internal part gets engorged with blood. On the other hand, when you're using a pump and putting a ring on it for intercourse, you're only getting the engorgement past the ring. This is why a pumped-erection often hangs down (called the ‘hinge effect’), can be a dusty blue colour, and is usually cooler to touch.

It’s important to note it's perfectly fine for the penis to not have a lot of blood flow for 30 minutes when you are using a pump and ring, as long as you release the ring after 30 minutes.

This is why men will often use both pumps and injections within their penile rehabilitation protocol. Some use a pump just for quick n easy daily rehab, but then injections are saved for sex. Others start with injections for sex, then down the line graduate to the pump and ring combo once some natural function returns so the erection is harder and more natural feeling.

What can you do if penile injection erections are painful?

This could be due to the injection 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. Especially if it’s been some time since you last had a full erection.

In the same way that your arm muscles will ache if you haven’t exercised for a while and then suddenly do a heavy weights session, the penile tissue needs regular stretch and blood flow to stay in top condition (check out our pump rehab guide on how to use a vacuum device to keep your penile tissue in excellent condition)

How often can someone use Penile Injections?

Honestly, every penile injection specialist we’ve spoken to has given a different answer to this question!

Tim Stewart does not recommend using penile injections more than twice a week. Whereas, Melissa Hadley-Barrett tells her patients that they can use the injections 48 hours apart, just definitely not more than once every 24 hours as it’s really important to have that gap of time otherwise you risk developing a Priapism (an erection that lasts too long).

Melissa says: “While you may have read that it is unsafe to inject more than two or three times a week maximum, the drug actually wears out after around 6 hours in the body”.

You can inject more regularly as long as you are keeping the penis tissue healthy by ensuring you change the site where you are injecting and using a pump between injecting

(Note: using an auto-injector can be a game changer for injecting regularly because it goes in quicker and causes less tissue damage).

What we’ve noticed they all agree on is to not inject in the same area too often. This is to avoid a build-up of scarring in that one area. This could over time even cause a bend in the penis, this is called Peyronie's Disease.

Alternate the injection site each time to prevent this.

Can the needle cause damage to the penis?

So long as you are doing the injection process correctly (see instructions above), the needle will not damage the penis. Also, make sure the needle is not bent before injecting. Always check beforehand that the needle is perfectly straight.

You might experience bruising at the site of injection, this is not uncommon, and it is not permanent or damaging. The bruising is caused by little capillaries bursting.

Again, just make sure you are alternating the site of injection to avoid scarring.

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.

For example, in a recent interview, Melissa Hadley-Barrett noted that many men taking a low-dose of PDE5 inhibitor (such as Viagra or Cialis) in the background (like a vitamin for your penis!) are fine to inject that same day.

Just note that your dose of injection will be different, you won't need as much of it because you've got a background dose of vasodilation. Essentially, it’s best to check with your prescribing doctor before embarking on combining these two erection-recipes.

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 (feel free to show them this guide as a starting point!).

You may be better off asking your Urologist for a prescription and a referral to a Penile Injection Specialist for training at the same time.

What if penile 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 much 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 same 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.

Follow this guide for using the Auto-injector with a partner (it is best if you have your correct dose first).

Should you 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 says: “Injections can be very good, but if you have a bad experience, then you won't want to go down that pathway again.” So do what you can do to make your first go a big thumbs up!

2. Get the appropriate dose for you. There are individual factors that affect the dosage. As we mentioned above, you need to avoid Priapism (prolonged erections lasting over 4 hours), but also find the right amount to induce a full erection for you. There’s a ‘Goldilocks’ moment for everyone and it might take some trial over time to find it.

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 (check the instructions section in this article).

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 as part of her service: “(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.”

Do penile injections aid in nerve recovery required for natural erections post Prostatectomy?

Here’s the thing, penile injections do not interact with those erection nerves. They are localised to the penile tissue. They create an erection on demand. But do not interact with the cavernous (erection) nerves at all.

BUT - that doesn't mean they don’t play a part in what we refer to as ‘penile rehabilitation’. Keeping the erectile tissue in top condition so that as those cavernous nerves recover, spontaneous erections have all the ‘well-oiled machinery’ (so to speak) necessary.

This is probably why clinical studies show mixed results when it comes to working out injections role in natural erection recovery. One research paper suggests that using ICIs post Prostate Surgery does improve erectile function down the line, and makes erection rehabilitation quicker. However, many other papers replicating this experiment do not mimic these findings.

In essence, the best way to think about it is that injection therapy is another way of ‘exercising’ the penis. This is a way to keep the penis healthy when nocturnal erections are not being produced.

So, injection therapy is a way of positively improving/maintaining your penile tissue health, but not necessarily the erection nerves.

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.