Reviewed by the Lucas Clinic Medical Team | Updated May 2026
Sildalis is a product marketed online that combines sildenafil citrate 100 mg and tadalafil 20 mg in a single tablet. Both sildenafil and tadalafil are PDE5 inhibitors — the same class of drugs used to treat erectile dysfunction (ED). Sildalis has no FDA approval, no MHRA licence, no EMA marketing authorisation, and no recognised approval from any major Western regulatory body. It is not a licensed pharmaceutical product in the US, UK, EU, Canada, or Australia. This page is informational, providing clinical context on why combining two PDE5 inhibitors in a single product is not medically sound, and directing patients toward appropriate licensed ED treatments.
Sildalis is manufactured and distributed from unregulated sources, primarily through online marketplaces operating outside regulatory frameworks. The clinical rationale for simultaneously combining a short-acting PDE5 inhibitor (sildenafil, effective for ~4–6 hrs) with a long-acting PDE5 inhibitor (tadalafil, effective for ~36 hrs) in a single dose is not supported by any peer-reviewed evidence or regulatory clinical trial data. The combination raises the same pharmacodynamic risks as either agent individually, while providing no evidence-based advantage over selecting one optimised agent at the right dose.
What Is Sildalis?
Sildalis combines two active ingredients that both inhibit PDE5: sildenafil (the active in Viagra) and tadalafil (the active in Cialis). Both work by the same mechanism — inhibiting the enzyme phosphodiesterase type 5, which breaks down cGMP in penile smooth muscle. Blocking PDE5 elevates cGMP, sustaining smooth muscle relaxation and increased blood flow to allow erection in the presence of sexual stimulation. Because sildenafil and tadalafil are pharmacodynamically additive at PDE5 receptors, combining them increases the magnitude of systemic vasodilation and the intensity of nitrate interaction risk. No licensed prescriber would simultaneously prescribe two PDE5 inhibitors.
Proponents of Sildalis claim the combination provides "the benefits of both" — sildenafil's faster onset and tadalafil's longer duration. In pharmacological reality, the risk profile is also compounded. Additive hypotension (potentially dangerous in patients with borderline blood pressure or who take antihypertensives), additive visual effects from PDE6 cross-reactivity, and the cardiovascular contra-indication regarding nitrates apply with increased severity. There is no minimum washout period between sildenafil and tadalafil — the two PDE5 inhibitors should never overlap in clinical practice.
Regulatory and Legal Status of Sildalis
Sildalis is not approved or licensed in: United States (FDA), United Kingdom (MHRA), European Union (EMA), Canada (Health Canada), Australia (TGA), or any comparable regulatory authority. It exists entirely outside the regulated pharmaceutical supply chain. Selling it constitutes distribution of an unlicensed medicinal product in all these jurisdictions — a criminal offence in the UK and an FDA violation in the US. Purchasing it online from foreign websites carries additional risks: importation of unapproved drugs is generally prohibited by customs regulations, and the product has not undergone any manufacturing quality review by a recognised authority.
Available Strengths and Forms
Sildalis is marketed in a fixed combination of sildenafil 100 mg + tadalafil 20 mg per tablet. These are the maximum approved doses of each component when used as single agents — prescribers selecting maximum sildenafil or maximum tadalafil monotherapy do so only in patients with demonstrated good tolerability at lower doses and appropriate cardiovascular screening. Combining maximum doses of both simultaneously has no clinical endorsement. No dose data from controlled clinical trials exists. Products sold under this name may contain varying actual quantities of each agent, as they originate from unverified manufacturing without GMP oversight.
Price Considerations
Sildalis is sold online at prices typically ranging from $0.50–$3 per tablet in bulk purchase packages, making it appear highly economical compared to branded ED medications. However, this price comparison is misleading: licensed generic sildenafil 100 mg (from FDA-approved US pharmacies with a valid Rx) costs approximately $1–$5 per dose via telehealth platforms, and licensed generic tadalafil is similarly priced. The apparent cost saving from unlicensed combination products does not account for the absence of manufacturing quality guarantees, medical screening, or legal supply chain protections. Patients seeking affordable ED treatment should consult a registered telehealth platform for legitimate, low-cost generic options.
Frequently Asked Questions
Is it safe to take sildenafil and tadalafil together?
No. Combining two PDE5 inhibitors simultaneously is not a medically accepted practice and is not recommended by any prescribing guideline or regulatory authority. Both drugs lower blood pressure via the same mechanism, and taking them together amplifies this effect. The only situation in which a prescriber would use sildenafil and tadalafil in the same patient is when switching from one to the other with an appropriate washout, or using low-dose daily tadalafil for BPH alongside sildenafil for ED at separate times — which even then requires careful clinical oversight. Never use both agents at the same time without specific medical direction.
Why is Sildalis not approved in the US or UK?
Because no manufacturer has submitted a new drug application (NDA) or marketing authorisation application (MAA) to the FDA or MHRA for a combination sildenafil/tadalafil product supported by clinical trial data. Regulatory approval requires randomised controlled trial evidence of safety and efficacy in the proposed indication. No such trials have been conducted for Sildalis or any sildenafil+tadalafil combination. Without that data, no legitimate regulatory body can approve the product. This is not a bureaucratic oversight — it reflects the absence of any clinical safety foundation for the product.
What are the approved alternatives for men who find sildenafil alone insufficient?
Men for whom sildenafil 100 mg (maximum dose) is insufficient should be evaluated by a urologist for possible organic causes of ED — vascular, hormonal, or neurological — rather than seeking higher-dose or combination unlicensed products. Switching to tadalafil (which works via the same mechanism but may have different inter-individual response) is a reasonable licensed option. Daily tadalafil 5 mg (the dose approved for daily use in ED) is another approach. Vacuum erection devices, intracavernosal prostaglandin injections (alprostadil), or surgical penile prosthesis placement are additional evidence-based escalation options.
Disclaimer: This page is for general informational purposes only and does not constitute medical advice. Always consult a licensed healthcare professional before making any treatment decisions. See our full disclaimer.