On this page Jump to a section
- Key facts
- What the labels say
- Label comparison table
- Why grapefruit matters (CYP3A4)
- How much and how long
- Grapefruit and Viagra
- Other CYP3A4 inhibitors
- What each path includes
- Safety checks before ED medication
- If ED is the problem you want treated now
- Mendoxa plans and prices
- FAQ
- How we wrote this
- Sources and references
Key facts at a glance
- Cialis label
- Grapefruit juice “would likely increase tadalafil exposure”; not studied directly, no grapefruit limit givenCIALIS (tadalafil) label §7.2
- Viagra label
- Grapefruit is not mentioned; sildenafil is eliminated mainly by CYP3A4VIAGRA (sildenafil) label §12.3
- No fixed waiting period
- Ask your pharmacist how much grapefruit, if any, you can have with your medicineFDA grapefruit guidance
- Compounded status
- The Mendoxa compounded tablet is not FDA-approvedFDA compounding Q&A
What the Cialis and Viagra labels say about grapefruit
The CIALIS label names grapefruit juice once, in its drug-interaction section: “Although specific interactions have not been studied, other CYP3A4 inhibitors, such as erythromycin, itraconazole, and grapefruit juice, would likely increase tadalafil exposure” (Cialis (tadalafil) label). “Would likely” matters: the label predicts a higher tadalafil level but reports no grapefruit study and no grapefruit-specific dose rule. The patient information section does not mention grapefruit.
The VIAGRA label does not mention grapefruit at all. We searched the full Viagra (sildenafil) label: it discusses CYP3A4 inhibitors such as ketoconazole, itraconazole, saquinavir, erythromycin and ritonavir, but not grapefruit.
Already prescribed treatment? Bring the exact product name to your interaction check. Our tadalafil guide and sildenafil guide explain the individual medicines.
Grapefruit and CYP3A4 rules on each ED drug label
Read these as two separate questions: does the label name grapefruit, and what does it require with inhibitor medicines? The limits below apply to the named medicines; they do not establish a grapefruit dose or waiting period (Cialis (tadalafil) label; Viagra (sildenafil) label).
| Drug | What the label says about grapefruit | Label limit with strong or potent CYP3A4 inhibitors | Source |
|---|---|---|---|
| Tadalafil (Cialis) | “other CYP3A4 inhibitors, such as erythromycin, itraconazole, and grapefruit juice, would likely increase tadalafil exposure.” Not studied directly. | As needed: “10 mg, not to exceed once every 72 hours.” Once daily: “maximum recommended dose is 2.5 mg.” | Cialis (tadalafil) label |
| Sildenafil (Viagra) | Grapefruit is not mentioned anywhere in the label. | “Consider a starting dose of 25 mg” with strong CYP3A4 inhibitors or erythromycin; with ritonavir, no more than a single 25 mg dose “in a 48 hour period.” | Viagra (sildenafil) label |
| Vardenafil (generic) | “other CYP3A4 inhibitors, including grapefruit juice would likely increase vardenafil exposure.” | Ritonavir or cobicistat: “No more than 2.5 mg in a 72-hour period”; ketoconazole 400 mg daily or clarithromycin: “No more than 2.5 mg in a 24-hour period.” | vardenafil label |
| Avanafil (Stendra) | “other CYP3A4 inhibitors, including grapefruit juice are likely to increase avanafil exposure.” | “Do not use STENDRA with strong CYP3A4 inhibitors”; moderate inhibitors: no more than 50 mg in 24 hours. | STENDRA (avanafil) label |
Sources: Cialis (tadalafil) label; Viagra (sildenafil) label; vardenafil label (DailyMed, Lannett); STENDRA (avanafil) label; APOKYN (apomorphine) label. Exact label wording, shortened with ellipses only where marked. Accessed Oct 31, 2026.
Why grapefruit can raise tadalafil levels
CYP3A4 is an enzyme that helps break down many medicines. Grapefruit juice can block its action in the small intestine, allowing more of an affected drug into the blood and keeping it in the body longer; the effect varies by person, drug and amount of juice (FDA grapefruit guidance).
The Cialis (tadalafil) label says tadalafil is metabolized predominantly by CYP3A4. That explains the concern about grapefruit, but the label does not measure a grapefruit-related increase in tadalafil levels.
How much grapefruit, and how long does it last?
There is no verified grapefruit serving size or waiting period for Cialis in these sources. The Cialis (tadalafil) label gives neither; FDA grapefruit guidance recommends asking your doctor or pharmacist how much grapefruit juice, if any, you can have.
A gap of a few hours is not a label-backed solution for tadalafil and grapefruit. Ask your pharmacist or prescriber about your next dose, including if you use daily tadalafil (Cialis (tadalafil) label). For a separate question about medicine duration, see how long Cialis lasts.
Check other citrus too. FDA says Seville oranges, pomelos and tangelos might have the same effect as grapefruit juice (FDA grapefruit guidance). Bring fruit, juice and mixed-drink ingredients to the conversation. Explore foods for erections, ED and alcohol and caffeine and ED for related questions.
Grapefruit and Viagra (sildenafil)
A small human study found higher sildenafil exposure with grapefruit juice. In a 2002 randomized crossover study, 24 healthy men received a single 50 mg sildenafil dose with 250 mL of grapefruit juice one hour before and again with the dose. Total exposure rose 23% compared with water; peak concentrations were essentially unchanged. The authors advised avoiding the combination. The Viagra (sildenafil) label discusses CYP3A4 inhibitors but does not name grapefruit.
This measured drug levels in healthy volunteers, rather than showing better erections or establishing a safe grapefruit amount. It does not establish a grapefruit rule for other ED medicines (sildenafil grapefruit study).
Medicines the labels name as CYP3A4 inhibitors
List exact medicine names, including short courses. The Cialis (tadalafil) label names ketoconazole, itraconazole, ritonavir and erythromycin in its CYP3A4 discussion. The Viagra (sildenafil) label also discusses ketoconazole, itraconazole, saquinavir, erythromycin and ritonavir; the required prescribing adjustments differ by medicine.
Use the label table to prepare questions for your prescriber. Do not use an inhibitor-medicine limit as your own grapefruit adjustment (Cialis (tadalafil) label; Viagra (sildenafil) label). If you already use another ED product, include it too; see Cialis and Viagra together.
What each path includes
Choose your next step by what you need help with today. If grapefruit is a regular part of your diet and you want ED treatment, an online visit lets you list it with your medicines from the start.
| Your situation | Starting point | What to discuss |
|---|---|---|
| I take Cialis and had grapefruit today | Your pharmacist or prescriber; FDA: grapefruit juice and some drugs | How much grapefruit or juice, when, and your tadalafil dose. The Cialis (tadalafil) label gives no grapefruit-specific wait time. |
| I also take an antifungal, antibiotic or HIV medicine | Your prescriber; Cialis (tadalafil) label and Viagra (sildenafil) label | Whether a strong CYP3A4 inhibitor applies to you and which ED dose limit fits. Prescription required. |
| I drink grapefruit juice daily and want ED treatment | Online visit or an in-person clinician | Your daily intake, other citrus, current medicines, blood pressure and alcohol use. |
| I want to know whether Mendoxa fits | Mendoxa online ED visit | Independent licensed providers assess suitability; the compounded tablet is not FDA-approved. |
Sources: FDA: grapefruit juice and some drugs; Cialis (tadalafil) label; Viagra (sildenafil) label; FDA compounding Q&A; Mendoxa care information. Accessed Oct 31, 2026.
Before your visit: note how often you have grapefruit, pomelo, Seville orange or tangelo products, every prescription and supplement you take, and when you last used an ED medicine. Questions to prepare: ED medication options.
Could Mendoxa ED care fit you?
Online ED visit · Prescription required · Independent licensed providers · Not available in California
Safety checks before ED medication
- Sildenafil and tadalafil are contraindicated with organic nitrates or riociguat (Viagra (sildenafil) label; Cialis (tadalafil) label).
- An erection lasting more than 4 hours needs immediate medical care (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Stop and seek care for sudden vision loss or sudden decrease or loss of hearing (Viagra (sildenafil) label; Cialis (tadalafil) label).
- The APOKYN (apomorphine) label contraindicates use with 5HT3 antagonists such as ondansetron and warns about nausea and fainting.
Give the prescriber your full medicine list, including antifungals, antibiotics and HIV medicines. See ED medication and nitrates for more detail.
If ED is the problem you want treated now
Ready to discuss ED treatment? Start the Mendoxa online visit with your grapefruit habits, current medicines and questions in one place. Independent licensed providers assess suitability. Prescription required.
The tablet combines sildenafil, tadalafil and apomorphine; it is not FDA-approved. Ingredient references are the Viagra (sildenafil) label, Cialis (tadalafil) label and APOKYN (apomorphine) label; APOKYN is an injectable Parkinson’s treatment, and its label is not approval of this ED combination. Because two ingredients are the CYP3A4-metabolized molecules described above, the provider needs your grapefruit and medicine details.
Use the visit to ask whether this option fits your health history. Learn about Mendoxa ED care and the combination ED tablet; available quantities and costs appear below.
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 31, 2026. The intake always shows the current price.
FAQ
Can you eat grapefruit with Cialis?
Ask your prescriber or pharmacist first. The Cialis (tadalafil) label names grapefruit juice as likely to increase tadalafil exposure; FDA grapefruit guidance advises checking whether grapefruit interacts with your medicine and how much, if any, you can have.
How long after grapefruit can I take Cialis?
The Cialis (tadalafil) label and FDA grapefruit guidance give no grapefruit-specific waiting period. Tell your pharmacist when and how much you had, your exact product and your prescribed dose, and ask about your next dose.
Can you take Tums with Cialis?
The Cialis (tadalafil) label reports slower absorption with a magnesium hydroxide/aluminum hydroxide antacid, without changing total exposure. It does not name Tums; ask a pharmacist about your specific antacid.
Why does grapefruit juice affect medications?
Grapefruit juice can block intestinal CYP3A4, an enzyme that breaks down many medicines, allowing more drug into the blood (FDA grapefruit guidance). Tadalafil depends on CYP3A4, and the Cialis (tadalafil) label predicts higher exposure with grapefruit juice.
How much Cialis can you take?
Your prescription determines your dose. With potent CYP3A4 inhibitor medicines, the Cialis (tadalafil) label limits as-needed use to 10 mg no more than once every 72 hours and daily use to 2.5 mg. These are medicine-specific limits, not a grapefruit dosing rule; ask your prescriber rather than adjusting your dose.
What are the health benefits of Cialis?
The Cialis (tadalafil) label lists treatment of erectile dysfunction, signs and symptoms of benign prostatic hyperplasia (BPH), or both. These indications do not establish a benefit from adding grapefruit; the label predicts increased tadalafil exposure.
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 compared the full DailyMed labels and FDA consumer guidance accessed Oct 31, 2026. The table separates grapefruit wording from limits for inhibitor medicines; those limits are not grapefruit dosing instructions. The cited labels describe separate approved products and do not establish the safety or effectiveness of Mendoxa’s compounded combination.
Updated Oct 31, 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 31, 2026.
- DailyMed: CIALIS (tadalafil) tablet, film coated, label revised 3/2026. Accessed Oct 31, 2026.
- DailyMed: APOKYN (apomorphine hydrochloride) injection, label revised 6/2022. Accessed Oct 31, 2026.
- FDA (Drugs@FDA): VIAGRA (sildenafil) prescribing information, NDA 020895. Accessed Oct 31, 2026.
- FDA (Drugs@FDA): CIALIS (tadalafil) prescribing information, NDA 021368. Accessed Oct 31, 2026.
- FDA: Compounding and the FDA, questions and answers. Accessed Oct 31, 2026.
- FDA: Grapefruit Juice and Some Drugs Don’t Mix (content current as of 07/01/2021). Accessed Oct 31, 2026.
- Jetter A, et al. Effects of grapefruit juice on the pharmacokinetics of sildenafil. Clin Pharmacol Ther. 2002;71(1):21-29. PMID 11823754. Accessed Oct 31, 2026.
- DailyMed: vardenafil hydrochloride tablets label (Lannett). Accessed Oct 31, 2026.
- DailyMed: STENDRA (avanafil) tablets label. Accessed Oct 31, 2026.
- Mendoxa ED care (product, format, max 1 dose per 24 hours). Accessed Oct 31, 2026.
- Mendoxa ED intake: plan prices (term_options). Accessed Oct 31, 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.