Sildalist (Sildenafil 100 mg + Tadalafil 20 mg): What the Evidence Says About Combining Viagra and Cialis

Sildalist is a tablet that combines two erectile dysfunction (ED) drugs: sildenafil 100 mg, the ingredient in Viagra, and tadalafil 20 mg, the ingredient in Cialis. It is sold as "dual action": the fast start of sildenafil with the long effect of tadalafil. A stronger version, Sildalist Strong, contains sildenafil 100 mg with tadalafil 40 mg.

We sell Sildalist and Sildalist Strong, so we have a commercial interest in this product. This guide still sets out what the evidence says, and it is less flattering than the marketing. Both ingredients are well studied on their own. The combination, at these doses, is not: no regulator we know of has approved it, both US labels say not to combine the two drugs, and no published trial has tested sildenafil 100 mg plus tadalafil 20 mg taken together. Every number below comes from a US drug label or a published study, listed at the end.

The short answer

Sildalist puts the maximum label dose of sildenafil (100 mg) and the maximum as-needed dose of tadalafil (20 mg) into one tablet. The Viagra label says combinations with other PDE5 inhibitors "have not been studied", "may further lower blood pressure" and are "not recommended". The Cialis label tells prescribers to inform patients not to take Cialis with other PDE5 inhibitors. The only trial we found that combined the two used much lower doses (tadalafil 5 mg daily plus sildenafil 50 mg when needed) and found no difference in adverse events between groups. If one tablet is not working well enough, the evidence-based next steps are a proper retry at the right dose, switching drugs, or daily low-dose tadalafil, which brought 4 in 10 partial responders to normal erectile function in two randomised trials. Sildalist Strong's 40 mg of tadalafil is double the maximum ED dose in the Cialis label.

What is in Sildalist

Product	Sildenafil	Tadalafil	Label maximum for ED
Sildalist (120 mg)	100 mg	20 mg	Sildenafil 100 mg; tadalafil 20 mg as needed
Sildalist Strong (140 mg)	100 mg	40 mg	Tadalafil 40 mg is twice the as-needed maximum

The "120 mg" and "140 mg" names add the two ingredients together. That number has no clinical meaning, because 1 mg of sildenafil and 1 mg of tadalafil are not equivalent: the label doses go up to 100 mg for sildenafil but only 20 mg for as-needed tadalafil.

How sildenafil and tadalafil work

Both drugs block the same enzyme, phosphodiesterase type 5 (PDE5). During sexual arousal, nerves in the penis release nitric oxide, which raises a messenger called cyclic GMP. Cyclic GMP relaxes the blood vessels and lets blood flow in. PDE5 breaks cyclic GMP down. Blocking PDE5 lets more of it build up, so the erection response is stronger. Neither drug causes an erection without sexual stimulation.

Because both block the same enzyme in the same way, a combination does not add a new mechanism. It adds more of the same effect, delivered on two time scales. That is the theory behind Sildalist, and also the reason the labels warn about it: the same enzyme block that widens penile arteries also widens blood vessels elsewhere and lowers blood pressure.

The idea behind combining them: fast start, long tail

The two drugs behave very differently in the body. Per their US labels:

Measure	Sildenafil	Tadalafil
Time to peak blood level	30 to 120 minutes (median 60), fasted	30 minutes to 6 hours (median 2 hours)
Mean terminal half-life	About 4 hours	17.5 hours
Effect of a high-fat meal	Peak delayed by about 60 minutes, peak level 29% lower	Label: may be taken without regard to food

The marketing logic is that sildenafil covers the first few hours while tadalafil covers the next day and a half. The problem is that both drugs are also active at the same time for the first several hours, which is exactly when their blood pressure effects can add up. Whether that matters in practice for most healthy men is unknown, because it has not been studied at these doses.

What the Viagra and Cialis labels say about combining PDE5 inhibitors

The Viagra label has a section titled "Combination with other PDE5 Inhibitors or Other Erectile Dysfunction Therapies". It says the safety and efficacy of such combinations "have not been studied", that "such combinations may further lower blood pressure", and "therefore, the use of such combinations is not recommended." Its patient leaflet says Viagra should not be used with other PDE5 inhibitors such as Adcirca, which is tadalafil.

The Cialis label says the safety and efficacy of combinations with other PDE5 inhibitors or ED treatments "have not been studied" and tells prescribers to "inform patients not to take CIALIS with other PDE5 inhibitors". Sildalist is, by definition, both drugs in one tablet.

Is Sildalist approved anywhere?

We found no sildenafil plus tadalafil combination in the US FDA's drug approval database, and we know of no regulator that has approved one. Sildalist is sold internationally through online pharmacies. In the US, Viagra, Cialis and their generics need a prescription, and a combination tablet like Sildalist is not an FDA-approved product. For the rules on importing and buying ED medicines in different countries, see our guide on buying sildenafil online in the US, UK, Canada and Australia.

What the research on combining them shows

We searched PubMed for trials that gave sildenafil and tadalafil together for ED. The evidence is thin:

• Cui 2015. 180 men with ED were assigned 1:1 to tadalafil 5 mg once daily, or tadalafil 5 mg daily plus sildenafil 50 mg as needed. Total erectile function scores were higher with the combination in men with severe ED, and some questions improved in men with moderate ED. The incidence of adverse events did not differ between groups. This is the closest study to Sildalist, but its doses are a quarter of the tadalafil and half of the sildenafil in each Sildalist tablet.
• Munk 2019 systematic review. Looking at men who had not responded to standard tablet treatment, the authors found that chronic tadalafil alone and tadalafil combined with sildenafil on demand "showed similar" improvements in erectile function scores.
• Mykoniatis 2021 meta-analysis. Across 44 studies of combination treatments for ED, adding daily tadalafil to PDE5 inhibitor treatment improved the erectile function score by 1.70 points on average (95% CI 0.79 to 2.61), but this result came from a single study.

No trial we found used sildenafil 100 mg with tadalafil 20 mg or 40 mg taken at the same time, which is what Sildalist and Sildalist Strong deliver.

Side effects of each ingredient at Sildalist doses

Since there is no data on the combination, the best available guide is what each ingredient does alone at the dose in Sildalist. These come from separate trial programmes, so they cannot be compared directly, and they cannot simply be added together.

Adverse reaction	Sildenafil 100 mg	Placebo	Tadalafil 20 mg	Placebo
Headache	28%	7%	15%	5%
Flushing	18%	2%	3%	1%
Indigestion (dyspepsia)	17%	2%	10%	1%
Abnormal vision	11%	1%	Not listed
Nasal congestion	9%	2%	3%	1%
Back pain	4%	2%	6%	3%
Muscle pain (myalgia)	4%	1%	3%	1%

Sildenafil figures are from the Viagra label's fixed-dose studies (100 mg n=506, placebo n=607). Tadalafil figures are from the Cialis label's as-needed studies (20 mg n=635, placebo n=476). The Viagra label notes that some side effects rise with dose, and that at doses above the recommended range adverse reactions "generally were reported more frequently". Abnormal vision with sildenafil was mostly a temporary color tinge, light sensitivity or blurring.

The blood pressure question

Blood pressure is the main reason the labels advise against combining PDE5 inhibitors. On their own, the effect is small in healthy men: the Viagra label reports a mean maximum fall of 8.4/5.5 mmHg in supine blood pressure in healthy volunteers, and the Cialis label reports a mean maximal fall of 1.6/0.8 mmHg relative to placebo with tadalafil 20 mg. These figures come from different study designs and cannot be compared directly.

The concern is about adding effects together, especially in men who also take an alpha blocker, other blood pressure medicines, or alcohol, or who have heart disease. The Viagra label says patients on alpha blockers should start sildenafil at 25 mg; Sildalist contains four times that, plus tadalafil. For anyone on these medicines, Sildalist is a poor fit.

Who must not take Sildalist

Because Sildalist contains both drugs, every contraindication and warning for either applies. Do not take it if you:

• use nitrates in any form, such as nitroglycerin sprays or tablets, isosorbide mononitrate, or recreational "poppers" (amyl nitrite)
• take riociguat (Adempas) for pulmonary hypertension
• already take sildenafil (Revatio) or tadalafil (Adcirca) for pulmonary hypertension, or any other ED medicine
• have been told sexual activity is unsafe for your heart
• are allergic to sildenafil or tadalafil
• have had a heart attack in the last 90 days, a stroke in the last 6 months, unstable angina or angina during sex, heart failure (NYHA class 2 or worse) in the last 6 months, uncontrolled heart rhythm problems, blood pressure below 90/50 mmHg or uncontrolled high blood pressure (the Cialis label says tadalafil is not recommended in these groups)
• have severe liver disease or retinitis pigmentosa (tadalafil not recommended)

The Cialis label says that if nitrates are needed in an emergency after tadalafil, at least 48 hours should pass first. With tadalafil's 17.5-hour half-life, that window applies to Sildalist too.

Who should avoid it or see a doctor first

The labels call for lower doses or caution in groups for whom a fixed 100 mg plus 20 mg tablet is unsuitable:

• men on alpha blockers (start sildenafil at 25 mg; start tadalafil at the lowest dose)
• men taking ritonavir (sildenafil maximum 25 mg in 48 hours; tadalafil maximum 10 mg once every 72 hours) or strong CYP3A4 inhibitors such as ketoconazole (tadalafil maximum 10 mg once every 72 hours; consider sildenafil 25 mg to start)
• men over 65 (consider sildenafil 25 mg to start)
• mild or moderate liver disease (tadalafil no more than 10 mg a day; consider sildenafil 25 mg to start)
• kidney disease with creatinine clearance below 50 mL/min (tadalafil capped at 10 mg every 48 hours, or 5 mg every 72 hours below 30 mL/min, where sildenafil should also start at 25 mg)
• any heart disease not listed above; the Viagra label has no controlled data after a heart attack, stroke or life-threatening rhythm problem in the last 6 months, or with blood pressure below 90/50 or above 170/110 mmHg
• previous sudden vision loss from NAION, Peyronie's disease, or conditions that raise the risk of priapism such as sickle cell anemia

Before using any ED medicine bought online, it is worth checking what a proper consultation should cover. Our guide to getting ED medication online lists the questions that matter.

Sildalist Strong: 40 mg of tadalafil

Sildalist Strong contains tadalafil 40 mg. The Cialis label's maximum for ED is 20 mg, taken no more than once a day. Tadalafil 40 mg once daily is the dose of Adcirca, a different product used for pulmonary arterial hypertension, not ED. The Cialis label reports that single doses up to 500 mg were given to healthy subjects with adverse events similar to lower doses, but that is safety data from controlled studies, not evidence that higher doses work better for ED. Our guide to tadalafil 40 mg, 60 mg and 80 mg covers what is known about doses above 20 mg.

Does Sildalist work better than one drug alone?

There is no trial that answers this. Each ingredient works well on its own: in their labels' trials, both sildenafil and tadalafil improved erections far more than placebo. What is missing is evidence that taking both at full dose adds benefit for a man who has not had a fair trial of one. Many men who think a tablet "doesn't work" have not used it correctly. Our guide on what to do when ED tablets don't work shows that in one study, 31 of 100 men referred as sildenafil non-responders responded once the dose and timing were corrected.

Better-studied options if one tablet is not enough

If a single tablet at the right dose has not given good enough erections, there are options with stronger evidence than a combination tablet:

• Retry properly. Use the full label dose your doctor considers safe, on several occasions, with sexual stimulation, and for sildenafil without a large or high-fat meal just before.
• Switch drugs. Some men respond better to tadalafil or vardenafil than to sildenafil. See our tadalafil vs sildenafil comparison.
• Daily low-dose tadalafil. Tadalafil 2.5 mg or 5 mg every day is an approved way to use it for ED. It has trial evidence in men who did not reach normal function on as-needed tablets (next section).
• Check testosterone. The AUA guideline says ED tablets may work better when combined with testosterone treatment in men with proven low testosterone.
• Non-tablet treatments. Alprostadil injections or pellets, vacuum devices and implants are all options the AUA guideline says should be discussed.

The evidence for daily tadalafil after a partial response

Two identical randomised, placebo-controlled trials (pooled in Kim 2014) enrolled men whose erections were still below normal while taking the maximum as-needed dose of sildenafil, vardenafil or tadalafil. After 12 weeks of daily tadalafil, the share who reached a normal erectile function score (26 or more on the IIEF erectile function domain) was:

Group	Men	Reached normal erectile function
Tadalafil 2.5 to 5 mg daily	207	39%
Tadalafil 5 mg daily	207	40%
Placebo	209	12.1%

The authors concluded that daily tadalafil improved erectile function in men with mild to mild-moderate impairment after as-needed treatment. It is one PDE5 inhibitor at a labelled dose, which keeps the blood pressure effect lower and is backed by randomised data. We sell daily-dose tadalafil such as Vidalista 5 and Tadarise 5.

If you still choose to take Sildalist

Some men will use Sildalist regardless. If you do, these points come from the labels of its two ingredients:

• Take no more than one tablet in 24 hours, and do not take any other ED medicine alongside it. Each tablet already contains the maximum label dose of both drugs.
• Avoid heavy drinking. The Cialis label says that substantial alcohol (for example 5 units or more) with tadalafil can increase orthostatic symptoms such as a faster heart rate, a drop in standing blood pressure, dizziness and headache.
• Stop and get medical help for chest pain, fainting, sudden vision or hearing loss, or an erection lasting more than 4 hours.
• Tell any emergency doctor that you have taken both sildenafil and tadalafil, because nitrates must be avoided.

Sildalist compared with taking the two drugs separately

Some men ask whether taking a Viagra and a Cialis together is the same as Sildalist. Pharmacologically it is very similar: the same two drugs at the same doses. The labels' advice is the same either way: do not combine them. A combination tablet does remove one option that separate tablets give you, which is the ability to use a lower dose of either drug.

Our view

Sildalist answers a question most men do not need to ask. For the majority, one well-used ED tablet at the right dose works. For those it does not help, the better-studied steps are a fair retry, a switch, daily tadalafil, a testosterone check, or a non-tablet treatment. We sell Sildalist, but we cannot point to evidence that it is better than a single drug, and both drug labels advise against the combination. If you are considering it, talk it through with a doctor first, and be wary of any seller that calls it a stronger or safer choice.

Sources

• VIAGRA (sildenafil citrate) US prescribing information, Pfizer, revised 08/2017, sections 2, 4, 5.1, 5.5, 5.6, 5.7, 6.1 Table 1, 10, 12.3 and Patient Information. DailyMed
• CIALIS (tadalafil) US prescribing information, Eli Lilly, revised June 2026, sections 2, 4, 5, 6.1 Table 1, 10 and 12.3. DailyMed
• ADCIRCA (tadalafil) US prescribing information, section 2.
• US FDA Drugs@FDA database (openFDA drugsfda endpoint), searched 16 October 2026 for products containing both sildenafil and tadalafil: no matches.
• Cui H et al. Efficacy and safety of long-term tadalafil 5 mg once daily combined with sildenafil 50 mg as needed at the early stage of treatment for patients with erectile dysfunction. Andrologia 2015;47(1):20-4. PMID 24387078.
• Munk NE et al. Systematic review of oral combination therapy for erectile dysfunction when phosphodiesterase type 5 inhibitor monotherapy fails. Sexual Medicine Reviews 2019;7(3):430-441. PMID 30711478.
• Mykoniatis I et al. Assessment of combination therapies vs monotherapy for erectile dysfunction: a systematic review and meta-analysis. JAMA Network Open 2021;4(2):e2036337. PMID 33599772.
• Kim ED et al. A return to normal erectile function with tadalafil once daily after an incomplete response to as-needed PDE5 inhibitor therapy. Journal of Sexual Medicine 2014;11(3):820-30. PMID 23841532.
• Burnett AL et al. Erectile Dysfunction: AUA Guideline. Journal of Urology 2018;200(3):633-641. PMID 29746858.
• Hatzichristou D et al. Sildenafil failures may be due to inadequate patient instructions and follow-up: a study on 100 non-responders. European Urology 2005;47(4):518-22. PMID 15774252.

This guide is for information only and is not medical advice. Do not combine ED medicines without a doctor's advice. Get emergency help for chest pain, fainting, sudden vision or hearing loss, or an erection lasting more than 4 hours.