Treatment category · 4 dedicated pages · FDA-approved · First-line ED treatment
Erectile dysfunction
medications — what works,
how they differ
ED medications are the established first-line treatment for erectile dysfunction — prescribed more than any other ED intervention. Understanding the differences between them helps you find the right option for your specific situation, lifestyle, and how your body responds.
ED medications don’t treat the underlying cause of ED — they create conditions for an erection to occur when arousal is present. For men who want to address root causes, regenerative and energy-based options on this site are worth exploring alongside or after establishing medication response.
How ED medications work
The mechanism — and why it matters
Most ED medications — Viagra, Cialis, Levitra, Stendra — belong to a class called PDE5 inhibitors. They work by blocking the enzyme phosphodiesterase type 5 (PDE5), which normally breaks down cyclic GMP in penile smooth muscle. By inhibiting this enzyme, they allow cyclic GMP to accumulate, smooth muscle to relax, and blood to flow into the penis during arousal.
This mechanism requires sexual arousal to be present — PDE5 inhibitors don’t cause erections independently, they enhance the vascular response to arousal. This is an important distinction many men don’t realize before their first prescription.
Trimix and Eroxon® work differently — Trimix bypasses the arousal requirement entirely by directly relaxing smooth muscle through injection, and Eroxon® is a topical gel that works via nitric oxide stimulation. Both serve specific populations for whom oral medications are insufficient.
All four options in this category are FDA-approved and work — but for different patients and situations. Oral PDE5 inhibitors are the starting point for most men. Trimix is for men who don’t respond adequately to oral medications or need a more reliable response. Eroxon® is a newer topical option for men who want to avoid oral medications or injections.
Vardenafil (Levitra®) and avanafil (Stendra®) are also FDA-approved PDE5 inhibitors. They work through the same mechanism as Viagra and Cialis with slightly different onset times, durations, and side effect profiles. They are covered in the comparison table below — Viagra and Cialis have dedicated pages because they are by far the most prescribed.
Block PDE5 → allow cGMP to accumulate → smooth muscle relaxes → blood flows in
Sexual arousal triggers nitric oxide release → nitric oxide activates guanylate cyclase → cyclic GMP (cGMP) produced → smooth muscle relaxes → blood inflow. PDE5 normally breaks down cGMP, ending the erection. PDE5 inhibitors block this breakdown, extending and enhancing the response.
Direct injection → smooth muscle relaxes → erection without arousal requirement
Trimix combines alprostadil, phentolamine, and papaverine — three agents that each relax penile smooth muscle through different pathways. Injected directly into the corpus cavernosum, it produces a reliable erection regardless of arousal state. Used when oral medications fail or produce insufficient response.
Medications with dedicated pages
Four options covered in depth
Click any card for the full page — mechanism, dosing, side effects, how to optimize response, and what to know before asking for a prescription.
Viagra® (Sildenafil)
The original PDE5 inhibitor — still the most prescribed ED medication worldwide. Fast onset, well-understood, widely available as affordable generic sildenafil. Affected by food — best taken on an empty stomach. The standard starting reference point for all other ED medications.
Cialis® (Tadalafil)
The “weekend pill” — lasts up to 36 hours compared to Viagra’s 4–6. Also available as a low-dose daily option for spontaneous sex without planning. Not affected by food. Often preferred by men who dislike timing their dose around sexual activity.
Trimix (Penile Injection)
A compounded injectable combination of alprostadil, phentolamine, and papaverine injected directly into the penis. Bypasses the oral absorption pathway entirely — highly reliable in men who don’t respond to PDE5 inhibitors. Works without arousal. Used for severe or medication-resistant ED.
Eroxon® (Topical ED Gel)
A newer OTC topical gel applied directly to the penis — FDA-cleared in 2023. Works via evaporative cooling to stimulate nitric oxide release and improve blood flow. Fast onset (about 10 minutes). No systemic absorption, no drug interactions. For mild to moderate ED in men who prefer avoiding oral medication.
Full comparison — all 6 options
Every approved ED medication side by side
Including Levitra® and Stendra® — which don’t have dedicated pages but are worth understanding if the main options haven’t worked for you.
| Medication | Type | Onset | Duration | Food effect? | Daily option? | Generic? |
|---|---|---|---|---|---|---|
| Viagra® (sildenafil) | Oral PDE5i | 30–60 min | 4–6 hours | Yes — high-fat meal delays | No | Yes — widely available |
| Cialis® (tadalafil) | Oral PDE5i | 30–60 min | Up to 36 hours | No effect | Yes — 2.5/5mg daily | Yes |
| Levitra® (vardenafil) | Oral PDE5i | 30–60 min | 4–6 hours | High-fat meal delays | No | Yes |
| Stendra® (avanafil) | Oral PDE5i | 15–30 min (fastest) | 6 hours | Minimal effect | No | Limited |
| Trimix | Injection | 5–15 min | 30–90 min | None | No | Compounded Rx |
| Eroxon® | Topical gel | ~10 min | 1–2 hours | None | No | OTC — no prescription |
Common questions
Frequently asked questions
Do ED medications work for everyone?
PDE5 inhibitors work for approximately 70–80% of men with ED. They are less effective when ED has a significant neurological component (e.g. after radical prostatectomy without nerve-sparing), when testosterone is very low, or when the dose or administration isn’t optimized. Men who don’t respond to one PDE5 inhibitor may respond better to another — or to a different dose or timing. Trimix is the reliable next step for oral medication non-responders.
Is generic sildenafil the same as Viagra?
Yes — generic sildenafil contains the same active ingredient at the same dose as brand-name Viagra. The FDA requires generic drugs to be bioequivalent to the brand. Generic sildenafil is dramatically less expensive and is the most cost-effective starting point for most men. The same applies to generic tadalafil vs. Cialis.
Can ED medications be combined with other treatments on this site?
Yes — and this is common clinical practice. Many men use shockwave therapy or PRP to address underlying vascular causes while continuing to use medication during the treatment period. PT-141 can be combined with a PDE5 inhibitor for both arousal and vascular support. TRT can be combined with PDE5 inhibitors if low testosterone is a contributing factor. Do not combine PDE5 inhibitors with nitrates — this is a dangerous interaction regardless of what other treatments you are using.
Do these medications cause dependency?
No — PDE5 inhibitors are not addictive and do not cause physical dependence. Some men experience psychological anxiety about sexual performance without medication after using it regularly — but this is psychological, not physical dependency. Some research suggests that regular use of PDE5 inhibitors (particularly daily tadalafil) may actually support penile tissue health over time by maintaining oxygenation — the opposite of a damaging effect.
Find an ED medication provider
Search our directory for vetted physicians — or join the forum to hear from men who have navigated different medication options.
PhallusMD is an informational resource and does not provide medical advice. All ED medications require evaluation by a licensed physician — particularly PDE5 inhibitors in men with cardiovascular disease. Never combine PDE5 inhibitors with nitrates. Viagra® is a trademark of Pfizer. Cialis® is a trademark of Eli Lilly. Levitra® is a trademark of Bayer. Stendra® is a trademark of Vivus. Eroxon® is a trademark of Futura Medical.