Can You Take Viagra and Cialis Together? 5 Safer Options

Can you take Viagra and Cialis together? Not on your own. Viagra (sildenafil) and Cialis (tadalafil) are both PDE5 inhibitors, and the FDA labels for both drugs say combining them with another PDE5 inhibitor has not been studied and is not recommended, because the effects on blood pressure can add up. If one tablet is not working, the safer route is to review how you take it, adjust the dose or switch with your doctor, or move to other erectile dysfunction treatment options. For how the two drugs differ when used separately, see our guide to Viagra vs Cialis.

Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; DailyMed (FDA label) — CIALIS (tadalafil) prescribing information

Can you take Viagra and Cialis together? The short answer

The short answer is no: do not mix Viagra and Cialis without a specialist’s plan. The FDA label for Viagra states that the safety and efficacy of combining it with other PDE5 inhibitors, with Revatio (sildenafil for lung hypertension) or with other ED treatments have not been studied, that such combinations may further lower blood pressure, and that their use is not recommended. The Cialis label tells prescribers to inform patients not to take Cialis with other PDE5 inhibitors, including Adcirca (tadalafil for lung hypertension).

The Viagra and Cialis labels also cap how often you take each drug. The maximum recommended dosing frequency for Viagra is once per day, and as-needed Cialis should not be taken more than once per day. Adding a second PDE5 inhibitor on top of the first works around this limit, which is exactly what the labels are designed to prevent.

Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; DailyMed (FDA label) — CIALIS (tadalafil) prescribing information

Patient guidance on Viagra and Cialis says the same thing in plain words. MedlinePlus advises that if you have side effects on sildenafil, you should not take more doses of sildenafil or similar medicines such as tadalafil (Cialis) or vardenafil (Levitra) until you talk to your doctor. It also notes that sildenafil is sold under several brand names and that you should use only one of these products at a time. The NHS lists other erectile dysfunction medicines among the drugs that may not mix well with sildenafil or tadalafil.

Sources: MedlinePlus — Sildenafil; NHS — Sildenafil (Viagra)

Why Viagra and Cialis do the same job

Sildenafil, tadalafil, vardenafil and avanafil all belong to one drug class: phosphodiesterase type 5 (PDE5) inhibitors. They relax and widen blood vessels by blocking the PDE5 enzyme, which is found in the penis and the lungs. With sexual stimulation, this lets more blood flow into the erectile tissue. None of them causes an erection without arousal.

Because the mechanism is the same, a second PDE5 inhibitor does not add a new way of working. It adds more of the same effect on blood vessels throughout the body, and therefore more of the same side effects. The main practical difference between Viagra and Cialis is timing. Sildenafil and its active metabolite have a half-life of about 4 hours, with peak levels reached within 30 to 120 minutes on an empty stomach. The NHS notes that the effects of tadalafil can last up to 36 hours.

Sources: Cleveland Clinic — Phosphodiesterase Inhibitors; DailyMed (FDA label) — VIAGRA prescribing information; NHS — Tadalafil

That long tadalafil window matters. If you take Cialis on Friday evening and a Viagra on Saturday, the tadalafil is likely still active, so Viagra and Cialis overlap even though you did not swallow them at the same moment. The same applies to men on daily tadalafil, who always have the drug in their system.

Sources: DailyMed (FDA label) — VIAGRA prescribing information; DailyMed (FDA label) — CIALIS prescribing information; EAU Guidelines — Management of Erectile Dysfunction

Risks of combining Viagra and Cialis

The most important risk of mixing Viagra and Cialis is a drop in blood pressure. Cleveland Clinic warns that PDE inhibitors can cause very low blood pressure, which might make you pass out, and that nitrates and alpha-blockers increase this risk. The Viagra label states plainly that combining PDE5 inhibitors may further lower blood pressure. Dizziness, light-headedness and fainting are the warning signs.

Dangerous add-ons: nitrates, poppers, alpha-blockers and alcohol

The EAU guidelines call the use of any organic nitrate or nitric oxide donor with a PDE5 inhibitor an absolute contraindication; nicorandil is also contraindicated. The Cialis label adds that at least 48 hours should pass after the last tadalafil dose before a nitrate is considered. The NHS warns that combining sildenafil or tadalafil with poppers (amyl nitrate) can increase the risk of serious side effects.

The Cialis label also advises caution with alpha-blockers, and lists alpha-blockers, blood pressure medicines and substantial amounts of alcohol (for example 5 units or more) as factors that can lead to low blood pressure. Stacking Viagra and Cialis on top of any of these raises the risk further.

Sources: Cleveland Clinic — Phosphodiesterase Inhibitors; EAU Guidelines — Management of Erectile Dysfunction; NHS — Tadalafil; DailyMed (FDA label) — CIALIS prescribing information

Priapism, vision and hearing problems

Priapism, an erection that will not go down, is listed by Cleveland Clinic as a severe side effect of PDE5 inhibitors. The Viagra and Cialis FDA labels both tell men to seek emergency treatment if an erection lasts more than 4 hours, because prolonged priapism can damage erectile tissue. Read more in our guide to priapism.

The Cialis label also says to stop the drug and get medical care for sudden loss of vision in one or both eyes, or a sudden decrease or loss of hearing. MedlinePlus gives the same advice for sildenafil. A larger total PDE5 inhibitor exposure does not make these rare events safer.

Sources: DailyMed (FDA label) — CIALIS prescribing information; MedlinePlus — Sildenafil

Unprescribed and mixed tablets

Combinations are often taken without a prescription, which removes the heart and medicine check a doctor would do. A Japanese forensic report described six deaths in which non-prescription PDE5 inhibitor use may have played a role. Three of the men who died suddenly had heart disease, which is a contraindication, and in one case blood tests found both tadalafil and vardenafil. A case series cannot prove cause, but the authors called for more public awareness of the risks of self-sourced tablets.

Source: PubMed — Association between sexual activity-related death and non-prescription use of PDE5 inhibitors (Nagasawa et al., Leg Med, 2021)

What studies show about combining PDE5 inhibitors

There is a small body of research on one specific combination: low-dose daily tadalafil plus an on-demand short-acting PDE5 inhibitor such as sildenafil, prescribed for men whose ED is hard to treat. This is very different from doubling up on full-strength Viagra and Cialis tablets at home.

The 2015 Andrologia trial

In a study from Nanjing, China, 180 men with ED were assigned either to tadalafil 5 mg once daily or to tadalafil 5 mg once daily plus sildenafil 50 mg as needed. Total IIEF-5 erectile function scores were significantly higher with the combination in men with severe ED, and adverse events did not differ between the groups. The trial was open-label and short, so it cannot settle long-term safety.

Source: PubMed — Efficacy and safety of tadalafil 5 mg once daily combined with sildenafil 50 mg as needed (Cui et al., Andrologia, 2015)

The 2021 meta-analysis and guideline view

A systematic review in JAMA Network Open pooled 44 studies of ED combination therapy (3,853 men). Adding daily tadalafil was linked to a 1.70-point improvement in IIEF score, but that result rested on a single study, the trial above. The authors noted high heterogeneity and that long-term benefits could not be evaluated. They suggested combination therapy be considered for refractory, complex or difficult-to-treat ED.

The EAU guidelines take a similar, cautious line. They list daily tadalafil with an on-demand short-acting PDE5 inhibitor among combination strategies for difficult-to-treat ED, while stressing that the available data are still limited.

Sources: JAMA Network Open (PMC) — Assessment of Combination Therapies vs Monotherapy for Erectile Dysfunction (Mykoniatis et al., 2021); EAU Guidelines — Management of Erectile Dysfunction

Research still under way

A randomized, placebo-controlled phase 4 trial at Mansoura University, Egypt, is recruiting men who did not respond to PDE5 inhibitors. It compares daily tadalafil 5 mg plus on-demand sildenafil 100 mg with daily placebo plus on-demand sildenafil, with an estimated 500 participants and a 12-week IIEF-5 outcome. No results are available yet.

Source: ClinicalTrials.gov — Daily Tadalafil 5 mg Combined With On-Demand Sildenafil 100 mg in PDE-5I Non-Responders (NCT07391579)

The bottom line: this combination is an off-label specialist option for selected men, with low starting doses, a cardiovascular check and follow-up. It is not evidence that taking Viagra and Cialis on the same night is safe.

Why one tablet may not be working

Most men who ask whether they can take Viagra and Cialis together are really asking why one tablet is not enough. The EAU guidelines say patient education can often rescue an apparent non-responder. Common, fixable reasons include:

• Timing: taking the tablet too close to sex, or expecting a result too soon.
• Food: a fatty meal can delay absorption of sildenafil, vardenafil and avanafil.
• No stimulation: PDE5 inhibitors need sexual arousal to work.
• Dose: the EAU starts sildenafil at 50 mg and on-demand tadalafil at 10 mg, adjusted to response and side effects.
• Low testosterone: men with hypogonadism may respond better to PDE5 inhibitors after testosterone therapy is started.

Source: EAU Guidelines — Management of Erectile Dysfunction

Our step-by-step guide on how to take Cialis covers timing, food and dosing in detail. If correct use still fails, the underlying cause of ED, such as diabetes, vascular disease or nerve damage after surgery, needs a proper assessment rather than a second pill.

Safer alternatives to taking Viagra and Cialis together

If one PDE5 inhibitor taken correctly is not enough, there are well-studied next steps that are safer than taking Viagra and Cialis together. Your urologist will choose based on your health, medicines and preferences.

1. Adjust the dose or switch drugs

Dose titration within the labeled range is the first step. Some men try a different PDE5 inhibitor, for example vardenafil, which the EAU notes is effective from 30 minutes after a dose. The guidelines are honest that randomized trials have not shown evidence that switching helps, so it is a reasonable trial rather than a proven fix.

2. Daily low-dose tadalafil instead of on-demand tablets

Once-daily tadalafil 5 mg gives a steady level and removes the need to time a tablet. The EAU finds no clinically significant difference in effectiveness between daily and on-demand tadalafil, so the gain is mainly spontaneity. The guidelines also advise reassessing daily use periodically.

Source: EAU Guidelines — Management of Erectile Dysfunction

3. Penile injections

Intracavernous injections of alprostadil act directly in the penis and do not rely on the PDE5 pathway. The EAU reports efficacy above 70% in the general ED population, with satisfaction of 87–93.5% in patients. Possible problems include prolonged erections (5%), priapism (1%) and fibrosis (2%), and drop-out rates of 41–68% have been reported. See our full guide to penile injections for erectile dysfunction.

4. Vacuum device or combination with a vacuum device

A vacuum erection device can work with efficacy as high as 90%, regardless of the cause of ED, though satisfaction varies widely (27–94%). It is not suitable for men with bleeding disorders or on anticoagulants. The EAU lists a PDE5 inhibitor plus a vacuum device among combination options for difficult cases.

5. Penile prosthesis

If other treatments fail, or by patient preference, a penile implant is an option. The EAU reports device survival of 93.3% at one year and 87.2% at five years.

Source: EAU Guidelines — Management of Erectile Dysfunction

Sources: EAU Guidelines — Management of Erectile Dysfunction; JAMA Network Open (PMC) — Combination Therapies vs Monotherapy for ED

What to do if you already took both

If you have taken Viagra and Cialis close together, do not take any more PDE5 inhibitor, avoid alcohol, and do not use nitrates or poppers. Sit or lie down if you feel dizzy, and get up slowly. The NHS advises contacting NHS 111 if you have taken more than your prescribed dose of sildenafil or tadalafil, and not to drive yourself if you are told to go to hospital. In the US, MedlinePlus lists the poison control helpline, 1-800-222-1222.

Call emergency services at once if you faint, have chest pain, trouble breathing, a seizure, or cannot be woken. Cleveland Clinic advises men who use nitroglycerin to go to the emergency room immediately if chest pain develops within 24 hours of a PDE5 inhibitor. Always tell emergency staff exactly which ED drugs you took, such as Viagra and Cialis, and when.

Sources: NHS — Sildenafil (Viagra); MedlinePlus — Sildenafil; Cleveland Clinic — Phosphodiesterase Inhibitors

When to see a doctor

Book an appointment if one PDE5 inhibitor taken correctly is not giving you a usable erection, if you are tempted to add a second ED drug (for example Viagra and Cialis together), or if you buy tablets without a prescription. Get emergency help for:

• An erection lasting more than 4 hours, or a painful erection.
• Chest pain, fainting or severe dizziness after an ED tablet.
• Sudden loss of vision in one or both eyes.
• Sudden loss or decrease of hearing, sometimes with ringing in the ears or dizziness.

Sources: DailyMed (FDA label) — CIALIS prescribing information; MedlinePlus — Sildenafil

If tablets are not enough, you can arrange a confidential consultation with our urologist-andrologist on WhatsApp to review your medicines and discuss safe erectile dysfunction treatment options. Treatment and any cost depend on the assessment.

FAQs about taking Viagra and Cialis together

Can you take Viagra and Cialis together on the same day?

Not unless a urologist has prescribed a specific plan. The Viagra and Cialis FDA labels limit each drug to once a day and advise against combining it with another PDE5 inhibitor, because the blood pressure effects add up. Tadalafil can act for up to 36 hours, so a Viagra taken the next day may still overlap with it.

Sources: DailyMed (FDA label) — VIAGRA prescribing information; NHS — Tadalafil

How long after Cialis can I take Viagra?

There is no official waiting time for switching between Viagra and Cialis, so ask your prescriber. Tadalafil’s effects can last up to 36 hours, so a Viagra taken within that window may still overlap with it. Do not take Viagra simply because a Cialis dose seemed weak.

Source: NHS — Tadalafil

Is it dangerous to take two ED pills at once?

It can be. Combining PDE5 inhibitors such as Viagra and Cialis may further lower blood pressure, which can cause dizziness or fainting, and the risk is higher with alcohol, alpha-blockers or blood pressure medicines. With nitrates or poppers, any PDE5 inhibitor can cause a dangerous drop. Seek urgent help for chest pain or fainting.

Sources: DailyMed (FDA label) — VIAGRA prescribing information; Cleveland Clinic — Phosphodiesterase Inhibitors

Do doctors ever prescribe sildenafil with daily tadalafil?

Occasionally, for selected men with hard-to-treat ED. The EAU lists daily tadalafil plus an on-demand short-acting PDE5 inhibitor as a combination strategy but notes the data are limited. One 180-man trial found better scores in severe ED without more side effects. It is off-label and needs specialist supervision.

Sources: EAU Guidelines — Management of Erectile Dysfunction; PubMed — Cui et al., Andrologia, 2015

What should I do if Viagra or Cialis stops working?

Check timing, food, arousal and dose first, since the EAU says education can rescue many apparent non-responders. Low testosterone, diabetes or vascular disease may also need treatment. If correct use still fails, ask about switching drugs, daily tadalafil, injections, a vacuum device or, eventually, an implant rather than taking Viagra and Cialis together.

Source: EAU Guidelines — Management of Erectile Dysfunction

Can I take Viagra if I am on Adcirca or Revatio?

No, unless your specialist says otherwise. Adcirca is tadalafil and Revatio is sildenafil, both used for pulmonary arterial hypertension. The Cialis label says not to take it with other PDE5 inhibitors including Adcirca, and MedlinePlus advises using only one sildenafil product at a time. Tell every prescriber about all PDE5 inhibitors you use.

Sources: DailyMed (FDA label) — CIALIS prescribing information; MedlinePlus — Sildenafil

Is daily Cialis stronger than taking Viagra and Cialis together?

Daily tadalafil is not a stronger drug; it keeps a steady low level so erections can happen without timing a pill. The EAU finds no clinically significant difference in effectiveness between daily and on-demand tadalafil. Its main advantages are spontaneity and staying within labeled, studied dosing, unlike self-combining Viagra and Cialis.

Source: EAU Guidelines — Management of Erectile Dysfunction