Trimix and Bimix injections
The most effective ED treatment there is, and the one nobody advertises
Our overall score
Written by J. Porter, MPH
Medically reviewed by R. Okafor, PharmD
Last reviewed
The short version
Trimix is a compounded blend of three drugs injected directly into the penis. It works in the large majority of men — including those for whom every pill has failed — costs a few dollars a dose, and takes effect in about ten minutes. It is also a needle, which is the entire reason you have never seen an advert for it.
Our verdict: Clinically, this is the strongest option on the site: highest success rate, lowest cost per dose, no nitrate contraindication. The barriers are real — self-injection, refrigeration, and a genuine priapism risk that demands respect — but for people who have run out of pills, nothing else comes close.
Best for: Anyone PDE5 inhibitors have failed, and anyone who wants the highest success rate at the lowest per-dose cost and can get past the needle.
What works
- Works for the large majority of users, including after prostate surgery and in advanced diabetes
- Very low cost per dose once you have a vial
- Fast — usable in roughly ten minutes
- No nitrate contraindication, so it remains available to many people with heart disease
- Does not depend on arousal signalling, so nerve damage does not defeat it
- Dose can be tuned precisely to give the duration you actually want
What to watch
- It is an injection into the penis, which rules it out for many people before anything else is considered
- Priapism risk is meaningfully higher than with oral medication
- Long-term use can cause scarring and plaque formation at injection sites
- Requires refrigeration and has limited shelf life
- Compounded, so quality depends heavily on which pharmacy fills it
- Papaverine carries a small risk of liver enzyme elevation
At a glance
- How it works
- A fine needle delivers a combination of vasodilators directly into the erectile tissue. Each drug works on a different pathway, so lower doses of each are needed and the erection does not depend on arousal signalling at all.
- Time to effect
- 5–15 minutes
- Safety limit
- An erection lasting more than 4 hours is a medical emergency
- How you get it
- Prescription only, filled by a compounding pharmacy. The first dose must be titrated in a clinic
- Regulatory status
- Trimix and Bimix are compounded combinations and are not FDA-approved. Alprostadil alone (Caverject, Edex) is FDA-approved for the same route
- Typical cost
- Often $50–$150 per vial, which typically yields many doses — commonly a few dollars per use
- Ongoing cost
- Refills every few weeks to months, depending on frequency and stability
- Clinical standing
- Intracavernosal injection is established second-line therapy in AUA guidance, recommended for people who do not respond to or cannot take PDE5 inhibitors
What is actually in the syringe
The names describe the arithmetic. Bimix contains two drugs, Trimix three. A less common Quadmix adds a fourth.
| Drug | What it does | Found in |
|---|---|---|
| Papaverine | A non-selective phosphodiesterase inhibitor that relaxes smooth muscle directly | Bimix, Trimix |
| Phentolamine | Blocks the alpha-adrenergic signalling that actively keeps the penis flaccid | Bimix, Trimix |
| Alprostadil (PGE1) | A prostaglandin that raises cAMP and relaxes the erectile tissue | Trimix only |
The reason for combining them is not redundancy — it is that each drug reaches the same destination by a different road. Because three mechanisms are contributing, each one can be used at a lower dose than it would need alone.
Why it works when everything else has failed
A PDE5 inhibitor preserves a signal your body generates during arousal. If the nerves that carry that signal were damaged during a prostatectomy, or by years of diabetes, there may be no signal to preserve — which is why pills so often disappoint in exactly those groups.
Injection therapy does not wait to be asked. The drugs act directly on the smooth muscle and the alpha-adrenergic tone in the erectile tissue. Arousal is not a prerequisite for the mechanism, which is both why the success rate is so high and why the dose needs to be right — an erection will happen whether or not the moment turns out to be convenient.
The first dose happens in a clinic
Titration usually starts low and increases across visits until a dose produces a firm erection lasting roughly 30 to 60 minutes. You will also be taught injection technique, which is the part people find far less daunting in practice than in prospect.
How the injection is actually done
The needle is very fine — comparable to an insulin needle — and the injection goes into the side of the shaft, not the top or the underside. That is deliberate anatomy: the urethra runs along the underside and the main nerves and vessels along the top.
- Alternate sides, and vary the site along the shaft, at every use
- Never inject into the top or the underside of the penis
- Clean the site with an alcohol swab and let it dry
- Apply pressure for a few minutes afterwards to limit bruising
- Never exceed one injection in 24 hours, and generally no more than about three per week
- Keep it refrigerated and respect the pharmacy's expiry date — potency falls off
Most people describe the injection itself as a minor sting. The more common complaint is a dull ache in the penis afterwards, from the drug rather than the needle.
Priapism: the risk that deserves real respect
This is manageable rather than disqualifying, and it is the single strongest argument for proper titration. Ask your prescriber, before you ever inject at home, what they want you to do if an erection passes the two- and three-hour marks — some will give you a specific plan. Know in advance which emergency department you would go to.
Long-term: scarring
Repeated injection into the same tissue can, over years, produce fibrosis — firm plaques or nodules at injection sites, occasionally with curvature. This is the main reason for the rotation discipline described above, and a reason to have the penis examined periodically rather than only when something feels wrong.
Papaverine specifically carries a small risk of raised liver enzymes and is thought to contribute more to fibrosis than the other components. Some prescribers use papaverine-free blends for this reason.
Compounding: when it is genuinely justified
We have been critical elsewhere on this site about compounded ED products — chewable sildenafil, for instance, where compounding buys you a format change and a price increase over an FDA-approved generic that already exists.
Trimix is the honest counter-example, and the distinction is worth understanding because it is the same word doing very different work.
That does not make the regulatory status irrelevant. Trimix is not FDA-approved, has not been through that review, and its quality depends on the pharmacy that made it.
The pharmacy matters more than usual
This is an injectable product going into vascular tissue, which raises the stakes on sterility well above an oral tablet. Compounded sterile injectables have a documented history of harm when quality control fails.
- 1Ask which pharmacy compounds it and whether they are state-licensed and in good standing.
- 2Ask about sterility practice — whether they compound under USP <797> sterile conditions.
- 3Ask about the beyond-use date and how the vial should be stored and transported.
- 4Inspect every vial before use. Discard anything cloudy, discoloured, or containing particles.
- 5Do not buy 'trimix' from any source that does not require a prescription. There is no legitimate version of that transaction.
The cost story
Injection therapy is one of the few places on this site where the most effective option is also among the cheapest — which is precisely why nobody markets it to you.
A vial typically yields many doses. Spread across those doses, the per-use cost commonly lands in low single-digit dollars — competitive with generic sildenafil and dramatically below single-use branded alprostadil syringes, which are priced per dose.
Who should not use it
- Sickle cell disease or other conditions predisposing to priapism — the risk compounds
- Anticoagulant therapy or bleeding disorders — relative caution; discuss it specifically
- Significant Peyronie's disease or existing penile fibrosis
- An existing penile implant
- Manual dexterity or vision problems severe enough to make safe self-injection unrealistic
- Anyone unable or unwilling to get emergency care for a prolonged erection
Where it sits against the alternatives
| Trimix injection | PDE5 pills | Vacuum device | |
|---|---|---|---|
| Success rate | Highest | Good, if nerves intact | High |
| Time to effect | 5–15 minutes | 30–60 minutes | 1–3 minutes |
| Cost per use | Very low | Very low (generic) | Effectively zero after purchase |
| Works with nerve damage | Yes | Often not | Yes |
| Safe with nitrates | Generally yes | No — absolute contraindication | Yes |
| Main barrier | It is a needle | Timing and food | Mechanical, kills spontaneity |
If you have tried pills at a proper dose without success, the realistic choice is between this and a vacuum device — and the honest framing is that one asks you to accept a needle and the other asks you to accept a pump. Plenty of people try both before deciding.
Common questions
How much does the injection hurt?
The needle is very fine and most people describe the stick itself as a minor sting, less than expected. The more common complaint is a dull ache in the penis afterwards, caused by the medication rather than the needle — and Trimix usually causes less of it than alprostadil alone, because it contains a lower dose of the component responsible.
Is Trimix FDA-approved?
No. Trimix and Bimix are compounded combinations prepared by a pharmacy, not manufactured under an FDA-approved application. Alprostadil on its own is FDA-approved for the same route as Caverject and Edex. In this case the compounding is doing real clinical work — no approved three-drug combination exists — but it does mean quality depends on the compounding pharmacy.
Can I use Trimix if I take nitrates for my heart?
Injection therapy does not carry the nitrate contraindication that makes PDE5 inhibitors dangerous, which is one reason it is considered for people with cardiac disease. It still requires medical evaluation, and sexual activity itself carries cardiac considerations worth discussing with your cardiologist.
What happens if the erection won't go down?
Past four hours, go to an emergency department — do not wait it out and do not sleep. Prolonged erection can permanently damage erectile tissue, and the risk is higher with injections than with pills. Ask your prescriber in advance what they want you to do at the two- and three-hour marks, and know which emergency department you would use.
How long does it last?
Typically 30 to 60 minutes at a properly titrated dose, though this is dose-dependent — which is much of the point of titrating it in a clinic rather than guessing.
How often can I inject?
Generally no more than once in 24 hours, and commonly no more than about three times a week. Rotate sides and vary the site each time to reduce the risk of scarring. Your prescriber will give you limits specific to your dose and formulation.
Does it need to be refrigerated?
Usually yes. Compounded Trimix has a limited shelf life and loses potency over time, so follow the storage instructions and beyond-use date your pharmacy provides. If a dose that used to work stops working, an expired or poorly stored vial is a common explanation.
Can I buy Trimix online without a prescription?
No legitimate source will sell it without one. It is a prescription compounded injectable requiring in-clinic dose titration, and a sterile injectable from an unverified source is a serious infection risk on top of the priapism risk of an unknown dose.
Sources
- 1.Erectile Dysfunction: AUA Guideline — American Urological Association
- 2.Treatment for Erectile Dysfunction — National Institute of Diabetes and Digestive and Kidney Diseases (NIH)
- 3.Compounding and the FDA: questions and answers — U.S. Food and Drug Administration