On this page Jump to a section
- Key facts
- What the Viagra and Cialis labels say about taking both
- Already took both? What to do now
- Same day, morning and night, or back to back?
- What each path includes
- Sildenafil vs tadalafil from the labels
- What the research actually shows
- Discuss a combination through a Mendoxa online visit
- Mendoxa plans and prices
- FAQ
- How we wrote this
- Sources and references
Key facts at a glance
- Direct answer
- Do not combine separate ED pills on your ownViagra (sildenafil) label · section 5.7
- Timing
- Tadalafil’s mean half-life is 17.5 hours in healthy subjectsCialis (tadalafil) label · section 12.3
- Evidence limit
- A small randomized study does not replace the combination warnings (Viagra (sildenafil) label; Cialis (tadalafil) label)PubMed · Cui et al.
- Mendoxa status
- The compounded tablet is not FDA-approved · Prescription requiredFDA · Compounding Q&A
What the Viagra and Cialis labels say about taking both
Both FDA labels address this directly. The Viagra (sildenafil) label (section 5.7) says combinations with other PDE5 inhibitors “have not been studied. Such combinations may further lower blood pressure. Therefore, the use of such combinations is not recommended.”
The Cialis (tadalafil) label (section 5.11) 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.” The Cialis patient leaflet is blunter: “Do not use other ED medicines or ED treatments while taking CIALIS.”
Already took both? What to do now
Contact your prescriber or pharmacist now and tell them exactly what you took, how much and when. Do not add another ED medicine while waiting for advice; the labels advise against combining treatments (Viagra (sildenafil) label; Cialis (tadalafil) label).
- An erection lasting more than 4 hours: seek emergency medical care, even if it does not hurt (Cialis (tadalafil) label).
- Chest pain, dizziness or nausea during sex: stop sexual activity and get medical help right away; tell the treating team when you last took an ED medicine (Viagra (sildenafil) label).
- Sudden vision loss or hearing decrease/loss: stop taking the medicine and contact a healthcare provider right away (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Nitrates or riociguat: do not combine these with either ED drug (Viagra (sildenafil) label; Cialis (tadalafil) label); read ED medication and nitrates.
Give the clinician your full list of prescription medicines, over-the-counter products and supplements. Alpha-blockers, blood pressure medicines and substantial alcohol consumption can increase the risk of low blood pressure with tadalafil (Cialis (tadalafil) label).
Same day, morning and night, or back to back?
Morning Cialis and nighttime Viagra are still an overlap concern: tadalafil’s mean terminal half-life is 17.5 hours in healthy subjects, according to the Cialis (tadalafil) label. The label reports improved erectile function up to 36 hours after an as-needed dose; that is not a waiting interval for adding sildenafil (Viagra (sildenafil) label).
Neither label gives a universal interval for switching between these drugs (Viagra (sildenafil) label; Cialis (tadalafil) label). Ask your prescriber when to stop one and start the other; do not treat a new calendar day or the end of a perceived effect as permission to add another pill.
Read how long Cialis lasts and how long Viagra lasts for the timing details to discuss at your visit.
What each path includes
Choose the situation that fits you, then take that question to the prescriber. The online intake is the place to ask whether a combination belongs in your care.
| Your situation | Next step | Prepare for the visit |
|---|---|---|
| You have not taken either pill | Do not start a two-drug regimen yourself (Viagra (sildenafil) label; Cialis (tadalafil) label). | Bring your current medicines and ED treatment history to an online visit. |
| One prescribed pill is not helping | Ask the prescriber to review use and tolerability before changing the dose (Viagra (sildenafil) label; Cialis (tadalafil) label). | Write down the medicine, timing, food and what happened; see ED pills not working. |
| You want to switch drugs | Get an individual switching schedule; neither label specifies a universal waiting interval (Viagra (sildenafil) label; Cialis (tadalafil) label). | Ask when to stop the current medicine and start the next; compare sildenafil vs tadalafil. |
| You take daily tadalafil | Do not add sildenafil on your own; daily use means continuous tadalafil exposure (Cialis (tadalafil) label; Viagra (sildenafil) label). | Review your prescription with the provider; see daily tadalafil. |
| You want to discuss a compounded combination | A licensed provider must decide whether it is appropriate; compounded drugs are not FDA-approved. | Start the Mendoxa intake and disclose everything you already take; see the combination ED tablet guide. |
Sources: Viagra (sildenafil) label; Cialis (tadalafil) label; FDA compounding Q&A. Accessed Oct 22, 2026. Visit preparation is editorial guidance, not a dosing schedule.
Could Mendoxa ED care fit you?
Online ED visit · Prescription required · Independent licensed providers · Not available in California
Sildenafil vs tadalafil from the labels (onset, duration, half-life, max dose)
People stack the two drugs to get sildenafil’s quicker peak together with tadalafil’s longer window. The figures below are what each FDA label states (Viagra (sildenafil) label; Cialis (tadalafil) label); the doses are the standalone brand-label doses, not a combination dose.
Time to peak blood level is different from onset time, and half-life describes drug elimination rather than how long an erection lasts. These standalone label doses are not a recipe for combining the drugs; individual conditions and other medicines can require lower doses or less frequent use (Viagra (sildenafil) label; Cialis (tadalafil) label).
| Label item | Sildenafil (Viagra label) | Tadalafil (Cialis label, as needed) |
|---|---|---|
| Onset guidance: when to take | About 1 hour before sex; anywhere from 30 minutes to 4 hours before (Viagra (sildenafil) label) | At least 30 minutes before anticipated sexual activity (Cialis (tadalafil) label) |
| Time to peak blood level | 30 to 120 minutes, median 60 minutes, fasted (Viagra (sildenafil) label) | 30 minutes to 6 hours, median 2 hours (Cialis (tadalafil) label) |
| How long it works | One study showed an effect up to 4 hours, diminished compared with 2 hours (Viagra (sildenafil) label) | Improved erectile function vs placebo up to 36 hours after dosing (Cialis (tadalafil) label) |
| Terminal half-life | About 4 hours (Viagra (sildenafil) label) | 17.5 hours (mean, healthy subjects) (Cialis (tadalafil) label) |
| Food | High-fat meal delays peak by a mean of 60 minutes (Viagra (sildenafil) label) | Absorption not influenced by food (Cialis (tadalafil) label) |
| Usual starting dose | 50 mg (Viagra (sildenafil) label) | 10 mg; once-daily ED use starts at 2.5 mg (Cialis (tadalafil) label) |
| Maximum dose | 100 mg (Viagra (sildenafil) label) | 20 mg as needed; 5 mg once daily (Cialis (tadalafil) label) |
| Maximum frequency | Once per day (Viagra (sildenafil) label) | Once per day in most patients (Cialis (tadalafil) label) |
| Combining with other PDE5 drugs | Not recommended; may further lower blood pressure (Viagra (sildenafil) label) | Not studied; do not take with other PDE5 inhibitors (Cialis (tadalafil) label) |
Sources: Viagra (sildenafil) label sections 2.1, 5.7, 12.2, 12.3; Cialis (tadalafil) label sections 2.1, 2.2, 5.11, 12.3, 17. Accessed Oct 22, 2026.
For a fuller comparison, read sildenafil vs tadalafil.
What the research actually shows
Cui et al. (2015), PubMed 24387078 reports a small randomized study of 180 men: tadalafil 5 mg daily alone versus the same regimen plus sildenafil 50 mg as needed. Those are study doses, not instructions for self-use; both labels warn against combining ED treatments (Viagra (sildenafil) label; Cialis (tadalafil) label).
| Finding in the abstract | What it cannot establish |
|---|---|
| Higher total IIEF-5 erection-questionnaire scores in the severe-ED subgroup with combined treatment | A benefit for every patient or every formulation |
| No difference in adverse-event incidence reported between groups | Proof that combining drugs is safe, or that rare harms are excluded |
Source: PubMed 24387078, Cui et al.; prescribing context: Viagra (sildenafil) label; Cialis (tadalafil) label. Accessed Oct 22, 2026.
This study compared separate medicines and did not test Mendoxa’s sildenafil + tadalafil + apomorphine tablet. It does not establish the safety or effectiveness of that compounded product, which is not FDA-approved; the Viagra (sildenafil) label and Cialis (tadalafil) label remain the prescribing references. The APOKYN (apomorphine) label is not a label for this ED combination.
Discuss a combination through a Mendoxa online visit
Mendoxa offers a compounded rapid-dissolve tablet containing sildenafil, tadalafil and apomorphine, as described on its ED care page. It is not FDA-approved. Independent licensed providers review the intake and decide whether to prescribe. Prescription required.
Provider review does not make a compounded tablet FDA-approved or establish that it is safer or more effective than either medicine alone. The Viagra (sildenafil) label and Cialis (tadalafil) label describe the approved standalone drugs; the APOKYN (apomorphine) label covers an injectable Parkinson’s treatment, not this ED tablet.
Disclose nausea medicines as well as ED medicines: the APOKYN (apomorphine) label lists a contraindication with 5HT3 antagonists such as ondansetron because profound low blood pressure and loss of consciousness have been reported. Ask the provider how your complete medicine list affects suitability.
Before the intake, gather your current prescriptions and a record of what you have tried. Read how much Viagra is too much if taking more has seemed like the next step. Your visit starts with that history, not a commitment to a prescription.
Mendoxa ED plans and prices
The Mendoxa ED tablet is a compounded rapid-dissolve tablet with sildenafil (the active ingredient in Viagra), tadalafil (the active ingredient in Cialis) and apomorphine (APOKYN label). It dissolves under the tongue. A licensed clinician decides if it fits you and selects the strength. Compounded medicines are not FDA-approved.
| Tablets per month | 1-month total | Per tablet (1 month) | 3-month total | Per tablet (3 months) |
|---|---|---|---|---|
| 6 tablets / month | $129 | $21.50 | $329 | $18.28 |
| 10 tablets / month | $149 | $14.90 | $379 | $12.63 |
| 20 tablets / month | $179 | $8.95 | $449 | $7.48 |
The 3-month total covers three months at the monthly tablet quantity shown.
If prescribed · Cancel anytime · Available in 49 states (not California). Prices from the Mendoxa intake at try.mendoxa.co/f/ed on Oct 22, 2026. The intake always shows the current price.
FAQ
Can you take Cialis in the morning and Viagra at night?
Not on your own. Tadalafil has a mean half-life of 17.5 hours (Cialis (tadalafil) label), so it is still active at night, and the Viagra (sildenafil) label says combining PDE5 inhibitors is not recommended because it may further lower blood pressure.
Can you take sildenafil and tadalafil in the same day?
Not as two separate self-chosen doses. Each label limits its drug to once per day, and both advise against combining it with other PDE5 inhibitors (Viagra (sildenafil) label; Cialis (tadalafil) label). A combination product is a prescriber’s decision after an intake.
How long after Cialis can I take Viagra?
Neither label sets a switching interval, so ask your prescriber. For context, the Cialis (tadalafil) label reports effects up to 36 hours and a 17.5-hour half-life; the Viagra (sildenafil) label reports a half-life of about 4 hours.
What should I do if I already took both?
Contact your prescriber or pharmacist with the names, amounts and times taken, and do not add another ED medicine (Viagra (sildenafil) label; Cialis (tadalafil) label). An erection lasting more than 4 hours needs emergency care; sudden vision or hearing loss needs immediate medical attention (Viagra (sildenafil) label; Cialis (tadalafil) label). See the warning-sign section above.
Is a sildenafil and tadalafil combination tablet the same as taking both pills?
Both involve the same PDE5 ingredients, so a prescription combination should not be read as an exception to the label warnings (Viagra (sildenafil) label; Cialis (tadalafil) label). Mendoxa’s tablet also contains apomorphine and is not FDA-approved; independent licensed providers decide suitability after an intake. Provider supervision does not prove that the combination is safer or more effective. The APOKYN (apomorphine) label describes a different, injectable product.
Is it safe to take Viagra with daily Cialis?
Do not add Viagra to daily Cialis yourself. Daily tadalafil produces continuous exposure, and the Cialis (tadalafil) label tells patients not to take it with other PDE5 inhibitors; the Viagra (sildenafil) label says combinations may further lower blood pressure. Ask the prescriber to review the existing prescription before making a change.
Ready to see if the Mendoxa ED tablet fits you?
From $129/month if prescribed · Cancel anytime · Available in 49 states (not California)
How we wrote this
Written by the Mendoxa editorial team · Sources: DailyMed/FDA. Medical facts on this page come from the FDA-approved labels on DailyMed and Drugs@FDA; each drug name links to its label. We checked the linked DailyMed labels, FDA compounding guidance and PubMed abstract on Oct 22, 2026. The comparison separates label timing, peak blood levels and half-life; these are not interchangeable. Study findings are reported as evidence from a small trial, not instructions to combine medicines. Mendoxa product details were checked on its ED page; the intake could not be fetched, so the fixed prices below reflect the supplied editorial brief rather than a fresh intake quote.
Updated Oct 22, 2026. This page is general information, not medical advice. A licensed clinician decides what fits you.
References
- DailyMed: VIAGRA (sildenafil citrate) tablet, film coated, label revised 12/2017. Accessed Oct 22, 2026.
- DailyMed: CIALIS (tadalafil) tablet, film coated, label revised 3/2026. Accessed Oct 22, 2026.
- DailyMed: APOKYN (apomorphine hydrochloride) injection, label revised 6/2022. Accessed Oct 22, 2026.
- FDA (Drugs@FDA): VIAGRA (sildenafil) prescribing information, NDA 020895. Accessed Oct 22, 2026.
- FDA (Drugs@FDA): CIALIS (tadalafil) prescribing information, NDA 021368. Accessed Oct 22, 2026.
- FDA: Compounding and the FDA, questions and answers. Accessed Oct 22, 2026.
- PubMed 24387078: Cui et al., Andrologia (2015), randomized sildenafil plus tadalafil study. Accessed Oct 22, 2026.
- Mendoxa ED care (product, format, max 1 dose per 24 hours). Accessed Oct 22, 2026.
- Mendoxa ED intake: plan prices (term_options). Accessed Oct 22, 2026.
About Mendoxa
Mendoxa (mendoxa.co) is a US telehealth brand. Independent licensed providers (licensed clinicians in the LocumTele network) review each online visit, and prescriptions are filled by Rush Pharmacy, a licensed US pharmacy. Available in 49 states (not California).
- Prescription required. A licensed clinician reviews every visit and can say no. A prescription is not automatic.
- A compounded medicine is not an FDA-approved finished product (FDA compounding Q&A).
- Plans: 1 month or 3 months, from $129. If prescribed · Cancel anytime · Available in 49 states (not California).
Compounded medication prescribed only if a licensed U.S. clinician decides it is appropriate. Not FDA-approved as a finished product. Not available in California. This site is not for emergencies. Call 911 if you need urgent care.