Trimix Intracavernosal Injection

Trimix intracavernosal injection is a combination of medications used for erectile dysfunction. These medications are injected directly into the side of the penis.

Trimix is a combination of 3 separate medications

  • Papaverine
  • Alprostadil
  • Phentolamine

Risks of Intracavernosal Injections:

  • Pain
  • Bleeding
  • Bruising
  • Priapism (see below)

Trimix should be stored in the refrigerator and away from light.

How to Inject

  1. Gather your supplies.
    • Medication vial
    • 1 syringe
    • 2 alcohol wipes
    • Sharps container
  2. Wash your hands.
  3. Wipe the top of the medication vial with an alcohol swab.
  4. Remove the cap from the needle on the syringe. Make sure that the needle does not come into contact with anything other than the medication vial.
  5. Withdraw air into the syringe. You want to withdraw approximately the same volume of air which you are going to be withdrawing from the vial.
  6. Insert the needle into the plastic stopper on the top of the medication vial. Push down on the stopper to inject the air into the vial.
  7. Turn the vial upside down and withdraw the correct amount of fluid (see below for correct dosage titration). You may need to withdraw more fluid initially to help clear out the air bubbles.
  8. Once you have the correct dose, withdraw the needle from the vial.
  9. Find a comfortable position either laying down or sitting.
  10. Grasp the head of your penis, and pull it out on stretch.
  11. Locate the area of your penis where you plan to inject. If you imagine your penis like a clock, you want to avoid 6 o’clock and 12 o’clock.
  12. Aim to inject either at 3 o’clock or 9 o’clock.
  13. Wipe the planned injection site with the alcohol swab.
  14. With the penis on stretch, insert the needle all the way into the erectile tissue of the penis.
  15. With the needle in position, push down on the syringe quickly. DO NOT move the needle while you are injecting.
  16. Once you have injected the medication, remove the needle and place pressure on the site for 2-3 minutes to prevent bruising.
  17. Place the syringe in the sharps container.

Finding the Correct Dose

This is a very important aspect of trimix injection teaching. Your urologist will give you an initial dose of the medication to start with. You will also be instructed how to titrate up the dose of your medication.

Important Information

  • DO NOT take more medication than prescribed
  • DO NOT use more than 1 injection in 24 hours
  • DO NOT give yourself another injection if the medication dose does not work
  • You can inject up to 3 times per week, as long as there is more than 24 hours between doses.

Please refer to the erection scale below


  • Joe was given his first dose in the clinic of 0.1 mL (10 units). This gave him an erection of 2/10.
  • Joe was instructed to increase his dose by 0.1 mL per treatment.
  • His second injection was 0.2 mL (20 units). This gave him an erection of 4/10.
  • Joe’s third injection was 0.3 mL (30 units). This gave him an erection of 7/10.
  • Joe’s fourth injection was 0.4 mL (40 units). This resulted in a 10/10 erection.
  • Joe’s dose for his trimix is 0.4 mL (40 units). He should continue to use this dose in the future.

What happens if my erection won’t go away?

This is called priapism, or an erection that lasts too long.

The pharmacy will provide you with a medication to try and counteract the trimix therapy. This is called pseudoephedrine HCl. If your erection is firm and lasts >3 hours, you should take 4 (30 mg) tablets of pseudoephedrine.

If your erection lasts more than 4 hours, you need to be seen at the emergency department. This is an emergency. Tell the emergency room staff that you have had an erection lasting more than 4 hours and that you have used trimix injection therapy. You will be seen on an urgent basis.