What duration is a Trimix dose aiming for?
About half an hour to an hour. Compounded Trimix has no FDA label of its own, so the targets come from alprostadil, the one Trimix ingredient sold as an FDA-approved injection on its own. MedlinePlus says an alprostadil injection erection should last approximately 30 to 60 minutes. The EDEX label calls an erection lasting no longer than one hour a standard treatment goal, and expects it to begin within 5 to 20 minutes.
That window is long enough for sex without a rush and short enough to keep a safe margin from the four-hour mark. Your provider applies the same logic to your Trimix dose.
How does dose titration get you there?
By starting low in the office and adjusting based on what actually happens. The AUA erectile dysfunction guideline says every man considering injections should have an in-office test injection first, to find a dose that gives a sufficient erection while keeping side effects low, and notes that it may take several visits. The CAVERJECT label describes the aim of titration as an erection suitable for intercourse that lasts no more than one hour, and says the patient should stay in the office until the erection fully subsides.
| What happens at a test dose | Typical next step |
|---|---|
| Too soft, or too short for sex | A slightly higher dose or a different mix, tested at the next visit |
| Firm, lasting about 30 to 60 minutes | That dose becomes your home dose |
| Lasting well over an hour | A lower dose next time, and closer monitoring |
Never skip ahead on your own. Memorial Sloan Kettering’s penile injection therapy guide tells patients not to change their dose without speaking to their provider and not to inject a second time if the first dose does not work.
Why might the erection outlast ejaculation?
Because the medicine keeps the blood vessels open whether or not you are still aroused. With a natural erection, or one helped by a pill, climax switches off the signal and blood drains away. Trimix acts directly on the erectile tissue, so the erection can continue after you finish, until the drug wears off. The MSK guide describes priapism, the main risk of injections, as an erection that does not go away after orgasm.
This is normal within your expected window and is not a sign of a problem by itself. It does mean you should not judge the dose by what happens after climax, and that the clock started at the injection, not at sex.
When does a long erection become a problem?
Once it runs well past your usual time, and certainly at four hours. In studies of CAVERJECT, 4% of men had an erection lasting four to six hours, and 0.4% had one lasting longer than six hours. That is why every man who starts injections should leave with a written plan that says when to call the clinic.
Emergency: An erection that has lasted four hours needs an emergency department now. Tell staff you used an ED injection, what it contained and when you injected. Our answer on an erection lasting more than four hours explains what happens there, and our page on priapism reversal with phenylephrine covers the medicine used.
How soon after injecting does it start?
Usually within minutes. The EDEX label expects an erection 5 to 20 minutes after injection, and MSK advises injecting about 5 to 15 minutes before you want the erection. Foreplay still helps the experience feel natural. Our guide to self-injecting Trimix walks through the technique, and our answer on whether Trimix injections hurt covers comfort.
How Ultimate Male sets your Trimix dose
At our San Gabriel and Downey clinics, your first dose is given and watched in the office, and you stay until the erection goes down. Your provider adjusts from there, and you leave with a written plan that includes your own call point for a long erection.
Read more about Trimix injections and the wider range of ED medications at Ultimate Male, or call 626-319-5261 for a free 10-minute call.
