Quad Rx for ED: Sildenafil, Tadalafil, Apomorphine & Vardenafil Explained
Quad Rx is Rx.com’s physician-prescribed, four-drug compounded treatment for erectile dysfunction (ED) that starts at $114 per month. Here is how each ingredient works, who may benefit, and what to know before you try it.
Quad Rx is a customized ED medication that combines apomorphine, sildenafil, tadalafil and vardenafil in a single sublingual liquid that dissolves under the tongue. By targeting multiple pathways that trigger an erection, the formula can help men who have not achieved reliable results with a single drug alone. Quad Rx is prescribed online by a licensed U.S. provider through Rx.com, shipped free to your door, and starts at $114 per month. The combination itself is not FDA-approved, so you and your doctor must weigh the benefits and risks carefully.
- A national survey finds erectile dysfunction affects 30% of U.S. men ages 40–70, and prevalence climbs to 62% in men over 70.(pmc.ncbi.nlm.nih.gov)
- Tadalafil’s 17.5-hour half-life allows up to 36 hours of erectile support, while vardenafil and sildenafil peak in about 1 hour.(dailymed.nlm.nih.gov)
- Quad Rx starts at $114 per month through Rx.com; brand Viagra can cost about $2,570 for 30 tablets.(drugs.com)
- The compounded mix is not FDA-approved as a product, so safety data come from the individual ingredients’ labels and studies.
- Contact a healthcare provider right away for chest pain, sudden vision changes, or an erection lasting more than 4 hours.
What Quad Rx Is - a four-drug compounded sublingual ED liquid
Quad Rx is a patient-specific compounded medication that contains apomorphine, sildenafil, tadalafil and vardenafil in customized strengths selected by your prescriber. Because these ingredients are blended in a 503A compounding pharmacy, the final product does not have its own FDA approval, even though sildenafil, tadalafil and vardenafil are each FDA-approved for ED individually and widely used as sildenafil, tadalafil and Levitra generics. Apomorphine, an oral dopamine agonist, is not FDA-approved for ED but has published efficacy data.(pubmed.ncbi.nlm.nih.gov)
Definition: Quad Rx is a prescription-only, multimodal erectile dysfunction therapy compounded for one patient at a time, delivered after an online visit, and priced from $114 per month through Rx.com.
Why no L-citrulline? Some blogs still list L-citrulline as the fourth ingredient, but Rx.com’s Quad Rx uses vardenafil instead. Make sure you confirm the actual formula with your prescriber before starting treatment.
How Each Ingredient Works to Produce an Erection
Sildenafil, tadalafil and vardenafil block the phosphodiesterase-5 (PDE-5) enzyme, which lets more cyclic GMP accumulate, relaxing penile smooth muscle so blood can flow in. The three drugs differ mainly in speed and duration (Table 1). Apomorphine activates dopamine D2 receptors in the brain’s paraventricular nucleus, triggering a reflex parasympathetic signal that initiates erection even before visual or tactile stimulation.(pubmed.ncbi.nlm.nih.gov)
| Ingredient | Typical onset* | Terminal half-life | Key advantage |
|---|---|---|---|
| Sildenafil | 30–60 min | 4 hours | Robust data, widely tolerated |
| Tadalafil | 30 min–6 h (median 2 h) | 17.5 hours | Up to 36 h “weekend” window |
| Vardenafil | 30–60 min | 4–5 hours | More PDE-5 selectivity than sildenafil |
| Apomorphine (sublingual data) | 10–20 min | 2 hours | CNS trigger may help severe neurogenic ED |
*Onset ranges come from FDA labels and published pharmacokinetic studies.(dailymed.nlm.nih.gov)
Why Combine Four ED Drugs Instead of Using One
Layering complementary mechanisms can increase the chances of a firm erection in men who do not respond fully to a single PDE-5 inhibitor. Apomorphine starts the neural signal, while the three PDE-5 blockers keep penile smooth muscle relaxed for longer. In practice, prescribers may use lower individual doses, aiming to:
Reduce dose-limiting side effects: splitting the workload means each drug can stay below the threshold that triggers flushing or nasal stuffiness.
Cover more time: tadalafil’s long half-life maintains responsiveness through the next day, while the quicker agents give an initial boost.
Break through comorbid barriers: Diabetes, post-prostatectomy nerve injury and vascular disease can blunt nitric-oxide signaling; adding a central dopaminergic kick from apomorphine may help.(pubmed.ncbi.nlm.nih.gov)
Who Might Benefit Most From Quad Rx
Men who have tried at least one standard ED pill at the maximum tolerated dose and still struggle with firmness or consistency are the main candidates. Typical Quad Rx candidates fall into one of three groups:
- Partial responders to sildenafil or tadalafil who lose rigidity mid-intercourse
- Men with ED plus metabolic syndrome or diabetes who need both fast and long coverage
- Post-surgical or spinal cord injury patients with neurogenic components
If you are new to ED treatment, first-line monotherapy remains appropriate. Check out our guide on how telehealth treats erectile dysfunction for the standard algorithm.
Safety & Side Effects: What to Watch For
Because Quad Rx contains multiple active ingredients, you may experience any side effect listed on each single-drug label. The most common are:
Flushing and headache: PDE-5 driven vasodilation, usually mild and transient.
Nasal congestion: more likely when sildenafil and vardenafil overlap.
Low blood pressure or dizziness: apomorphine adds dopaminergic vasodilation; check baseline BP.
Back pain and muscle aches: traced to tadalafil’s PDE-11 activity.
Drug interactions: Do not combine with nitrates, riociguat or potent CYP3A4 inhibitors. Review our full tadalafil safety guide for details.
Is Quad Rx a good fit for tonight’s plan?
Check the column that fits your situation:
✅ Likely OK
- BP controlled and above 100/60 mm Hg
- No chest pain medications (nitrates) in the last 48 hours
- Normal vision, no retinitis pigmentosa
- Able to delay alcohol to ≤2 drinks
🏥 Talk to a doctor first
- Recent heart attack or stroke (<6 months)
- Resting low BP (<90/50 mm Hg) or uncontrolled arrhythmia
- Current nitrate or riociguat therapy
- Severe liver or kidney impairment (eGFR <30 mL/min)
- Erection lasts over 4 hours (seek ER care)
How to Use Quad Rx and What to Expect
Your prescriber will set individualized strengths and dosing instructions, but most men take one capsule 30–60 minutes before planned sexual activity. Because tadalafil remains active for a day and a half, you may find morning dosing covers both evening and next-day encounters.
Meal size and timing: High-fat meals can delay sildenafil and vardenafil absorption.(drugs.com) A lighter snack helps maintain quick onset.
Alcohol: Limit to two standard drinks, as heavier intake compounds low blood pressure risk.
Tracking results: Keep a simple erection score diary (0 = no response, 4 = fully rigid). Share at follow-up so your provider can adjust the mix.
| ED Option | Approx. cash price / month | Dose frequency |
|---|---|---|
| Brand Viagra 50 mg (30 tabs) | $2,570 | As needed |
| Generic sildenafil 100 mg (30 tabs) | $10–20 | As needed |
| Brand Cialis 5 mg (30 tabs) | $289 | Daily |
| Generic tadalafil 5 mg (30 tabs) | $10–30 | Daily |
| Quad Rx | $99 | Customized (often once daily) |
Prices from Drugs.com price guides accessed September 2026.(drugs.com)
💡 Compare local prices instantly
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Cost & How to Get Quad Rx Online
Quad Rx starts at $114 per month, which includes a free provider consultation, the medication and free express shipping. You pay the same price at every renewal, and you are billed only if a prescription is approved.
Step-by-step:
- Complete a secure questionnaire and optionally upload recent labs.
- A licensed U.S. provider reviews your history and may request video chat if needed.
- If approved, a 503A partner pharmacy compounds your personalized capsules.
- Medication ships discreetly to your door in 2–4 days.
- Follow-up messaging lets you tweak the formula at no extra cost.
You can also discuss Quad Rx with your in-person urologist and transfer the prescription, thanks to Rx.com’s online prescription transfer system.
🚨 When to Contact Your Healthcare Provider
Contact your doctor immediately if you experience any of the following:
- Chest pain or shortness of breath - could indicate cardiac ischemia
- An erection lasting more than 4 hours - risk of permanent tissue damage (priapism)
- Sudden loss of vision in one or both eyes - may signal NAION
- Sudden loss of hearing or ringing in the ears - rare ototoxic reaction
- Severe dizziness or fainting - possible dangerous drop in blood pressure
- Allergic swelling of lips, tongue or throat - potential anaphylaxis
- Severe back or muscle pain unrelieved by OTC analgesics
- Nausea, vomiting or sweating with sexual activity - could signal cardiac stress
Scientific References
- Rosen RC et al. Randomized, double-blind, crossover trial of sildenafil in men with mild to moderate erectile dysfunction. J Sex Med. 2008.
- Heaton JP et al. European multicentre study of sublingual apomorphine dose escalation in erectile dysfunction. BJU Int. 2002.
- FDA. Viagra (sildenafil citrate) Prescribing Information. Updated 2026.
- FDA. Tadalafil Prescribing Information. Updated 2026.
- FDA. Vardenafil Prescribing Information. Updated 2026.
- Sharma R et al. Population-based survey of erectile dysfunction among U.S. men in 2021. J Urol. 2022.
- Khera M et al. Evaluation of apomorphine for the treatment of erectile dysfunction. Expert Opin Pharmacother. 2012.
- Drugs.com. Viagra Prices. Accessed September 2026.
- Drugs.com. Cialis Prices. Accessed September 2026.
Frequently Asked Questions
Does Quad Rx work the first time you take it?
Many men notice improved rigidity after the first dose, especially from the fast-acting sildenafil and vardenafil components. However, optimal response can take 2–4 tries while your provider fine-tunes strengths.
Can I take Quad Rx every day?
Yes, some prescribers design a once-daily regimen that leverages tadalafil’s long half-life. Follow the exact instructions on your prescription label.
Is Quad Rx safe with alcohol?
Light drinking (≤2 drinks) is generally tolerated, but larger amounts raise the risk of low blood pressure and dizziness. Avoid binge drinking on treatment days.
Why does Quad Rx cost less than brand Viagra?
Because it is compounded, Quad Rx uses generic active pharmaceutical ingredients and is not marketed by a brand manufacturer, allowing lower pricing.
Is the medication a capsule or a troche?
Quad Rx is compounded as a sublingual liquid that dissolves under the tongue, so there is no pill to swallow and no injection.
Can I split the capsule to adjust dose?
No. The ingredients are blended throughout the fill material, so splitting would give uneven amounts. Ask your provider for a lower-strength prescription instead.
Does Quad Rx show up on a drug test?
Standard workplace drug screens do not test for PDE-5 inhibitors or apomorphine. Specialized labs could detect them, but this is uncommon outside sport anti-doping panels.
Can women use Quad Rx?
The combination has not been studied for female sexual dysfunction and is not prescribed for women through Rx.com.
