Tadalafil and Sildenafil Together: What to Know

PrescribedRX is a patient management and marketing platform that does not dispense medications; all medical services are delivered by independently licensed healthcare professionals, and all prescriptions are issued solely at the discretion of the licensed provider (PrescribedRX product page footer).

Short answer: Whether taking sildenafil and tadalafil together, or a single tablet that contains both, is appropriate for you is decided by a licensed provider who reviews your health history and current medications. The Viagra and Cialis prescribing information each describe one drug taken on its own (Viagra prescribing information; Cialis prescribing information). A small body of research has tested daily tadalafil plus as-needed sildenafil taken as separate pills, with mixed results (Cui 2015; Munk 2019; Mykoniatis 2021).

Choosing between the two instead? See our full sildenafil vs tadalafil comparison.

Can you take sildenafil and tadalafil together?

That decision belongs to a licensed provider who reviews your health history and every medicine you take, including any heart or blood pressure medicines. Sildenafil (the active ingredient in Viagra) and tadalafil (the active ingredient in Cialis) belong to the same drug class, PDE5 inhibitors, and the prescribing information for each covers that drug alone (Viagra prescribing information; Cialis prescribing information). The sections below cover how the two drugs differ, what the published research on combining them reports, and what to share with a provider.

How do sildenafil and tadalafil differ?

• How fast they start and how long they last. The AUA lists sildenafil as starting in 30 to 60 minutes and lasting up to 12 hours, and tadalafil as starting in 60 to 120 minutes and lasting up to 36 hours (AUA Table 3).
• How long each drug stays in the body. The Cialis prescribing information gives tadalafil’s mean terminal half-life as 17.5 hours (Cialis prescribing information, 12.3), and its patient leaflet says some of a single dose stays in your body for more than 2 days (Cialis patient information). Sildenafil’s half-life is about 4 hours (Viagra prescribing information, 12.3).
• Common side effects. Both documents list headache, flushing, indigestion and nasal congestion among the most common side effects of each drug (Viagra prescribing information, 6; Cialis prescribing information, 6). See our guide to tadalafil side effects.

	Sildenafil (Viagra)	Tadalafil (Cialis)
Onset and duration (AUA)	30 to 60 minutes; up to 12 hours	60 to 120 minutes; up to 36 hours
Half-life (prescribing information)	About 4 hours	17.5 hours mean

Our guide to every ED treatment option covers alternatives to both drugs.

Is there any research on combining sildenafil and tadalafil?

• Cui et al., 2015 (Andrologia). Researchers in Nanjing, China, assigned 180 men with ED 1:1 to tadalafil 5 mg once daily, or the same plus sildenafil 50 mg as needed. The abstract reports that total IIEF-5 scores in men with severe ED were significantly higher with the combination than with daily tadalafil alone. The two drugs were given as separate pills on different schedules, and the abstract does not describe a single tablet containing both (Cui 2015).
• Munk et al., 2019 (Sexual Medicine Reviews). This systematic review covered oral combination therapy in men whose single-drug PDE5 inhibitor treatment had not worked. It reports that chronic tadalafil alone or with on-demand sildenafil “showed similar IIEF-5 score improvements.” The regimen it describes uses separate pills on different schedules, and the abstract does not describe a single tablet containing both (Munk 2019).
• Mykoniatis et al., 2021 (JAMA Network Open). In a meta-analysis of 44 studies and 3,853 men, the authors report that adding daily tadalafil was associated with a 1.70-point IIEF improvement (95% CI 0.79 to 2.61), based on only 1 study, and that heterogeneity remained high. The abstract does not describe a single tablet containing both drugs (Mykoniatis 2021).

What do urology guidelines say?

The 2018 AUA guideline says men with ED should be informed about oral PDE5 inhibitors, including benefits and risks, unless they are contraindicated (AUA St. 8). It says “more than one trial with the medication may be required to establish efficacy,” and that incorrect use, such as no sexual stimulation or taking the pill with a large meal, accounts for 56% to 81% of treatment failures (AUA St. 9). It also says the dose should be titrated to provide optimal efficacy (AUA St. 10).

As part of finding the optimal dose, the guideline says men “may be offered dosing frequency changes or different PDE5i” (AUA St. 10). That refers to switching to a different PDE5 inhibitor, and the guideline statements cited here do not address taking two PDE5 inhibitors together.

What is PrescribedRX’s Prime Time?

Prime Time is a compounded tablet offered through PrescribedRX. Compounded medications are prepared by licensed pharmacies and are not FDA-approved. Its product page lists the following (Prime Time product page):

• What it is: tadalafil and sildenafil in one tablet. Six pills a month on the 6-pill plan; a separate 12-pills-a-month plan is listed as 36 pills.
• Price shown for the 6-pill plan: 3 month plan $201 · $67/mo · Billed every 3 months. Cancel anytime.
• Prescribing: a licensed provider decides whether it is appropriate for you, and your provider sets the dose.

What to tell a provider about ED medicines you take

• Every medicine you take, including heart medicines, blood pressure medicines, alpha blockers and recreational drugs. The Viagra and Cialis patient information both ask you to tell your provider about all the medicines you take (Viagra patient information; Cialis patient information).
• Your heart history and any other health conditions.
• Whether the dose of the drug you take now has been adjusted; the AUA says the dose “should be titrated to provide optimal efficacy” (AUA St. 10).
• When you last took a PDE5 inhibitor. The Cialis patient information says it is important for your provider “to know when you last took CIALIS” (Cialis patient information).

For general background, see our ED safety information.

Frequently asked questions

Can you take Cialis in the morning and Viagra at night?

Whether any combination of ED medicines is appropriate is decided by a licensed provider who reviews your health history and current medications. One timing fact is relevant to that conversation: tadalafil’s mean half-life is 17.5 hours (Cialis prescribing information, 12.3), and some of a single dose remains in your body for more than 2 days (Cialis patient information).

Is there a pill that combines Viagra and Cialis?

The Viagra and Cialis prescribing information each cover one drug, and neither describes a tablet containing both (Viagra prescribing information; Cialis prescribing information). PrescribedRX offers a compounded combination tablet, Prime Time, and a licensed provider decides whether it is appropriate for you (sexual health page).

Does a combination work better than one drug?

The evidence is limited: the meta-analysis described its daily-tadalafil result as “based on limited data” (Mykoniatis 2021). One trial of 180 men reports higher total IIEF-5 scores in men with severe ED with daily tadalafil plus as-needed sildenafil than with daily tadalafil alone (Cui 2015). A systematic review reports similar improvements with daily tadalafil alone or with on-demand sildenafil (Munk 2019). None of these abstracts describes a single tablet containing both drugs.

Who decides whether a combination is right for me?

A licensed provider, after reviewing your health history and current medications. All prescriptions through PrescribedRX are issued solely at the discretion of the licensed provider (product page footer).

Discussing ED treatment with a provider

If you want to discuss ED treatment options, see our online ED treatment options; a prescription is issued only if a licensed provider determines treatment is appropriate (sexual health page). You can also read how sildenafil and tadalafil prescriptions work here.

Sources

1. Viatris. VIAGRA (sildenafil) prescribing information, revised 11/2023. DailyMed. dailymed.nlm.nih.gov. Accessed Oct 2026.
2. Eli Lilly. CIALIS (tadalafil) prescribing information, revised 3/2026. DailyMed. dailymed.nlm.nih.gov. Accessed Oct 2026.
3. Burnett AL, et al. Erectile Dysfunction: AUA Guideline. J Urol. 2018;200:633. American Urological Association. auanet.org. Accessed Oct 2026.
4. Cui H, et al. Tadalafil 5 mg once daily combined with sildenafil 50 mg as needed for ED. Andrologia. 2015;47(1):20-4. PubMed. Accessed Oct 2026.
5. Munk NE, et al. Oral combination therapy for ED when PDE5 inhibitor monotherapy fails. Sex Med Rev. 2019;7(3):430-441. PubMed. Accessed Oct 2026.
6. Mykoniatis I, et al. Combination therapies vs monotherapy for ED: a meta-analysis. JAMA Netw Open. 2021;4(2):e2036337. PubMed. Accessed Oct 2026.
7. PrescribedRX. Prime Time product page and site footer. prescribedrx.com/plans/prime-time/. Accessed Oct 2026.
8. PrescribedRX. Sexual Health page. prescribedrx.com/sexual-health/. Accessed Oct 2026.

This article is for general information. It is not medical advice and it is not a recommendation for any particular treatment. Whether a treatment is appropriate for you is a decision for a licensed clinician who has reviewed your health history and current medications.