Can You Take Viagra And Cialis Together?

Taking Viagra and Cialis together is generally not recommended unless a healthcare professional has specifically advised it. Viagra contains the active ingredient sildenafil, and Cialis contains tadalafil and both belong to the same family of medicines called PDE5 inhibitors, which work in very similar ways to treat erectile dysfunction (ED). Combining them does not necessarily give you a stronger or longer-lasting erection, but it can raise the chances of side effects.

It’s a common assumption that “more is better,” but with these medicines that’s simply not how they work. Below, we break down why combining them isn’t routine, what can happen if you do, and what to do instead.

Understanding How Viagra and Cialis Work

➤ Viagra (Sildenafil)

Sildenafil was originally developed to treat pulmonary arterial hypertension, but it became widely known for treating ED. It works by inhibiting phosphodiesterase type 5 (PDE5), an enzyme that breaks down cyclic guanosine monophosphate (cGMP).

By blocking PDE5, Viagra increases cGMP levels in penile smooth muscle, causing blood vessels to relax and dilate facilitating an erection in response to sexual stimulation.Its effects typically last around 4 to 6 hours, although the actual duration can vary between individuals. For more detail, see our guide on how long sildenafil lasts.

Drug Facts

➤ Cialis (Tadalafil)

Tadalafil works through the exact same PDE5-inhibiting pathway as sildenafil, making it pharmacologically similar. However, Cialis has a significantly longer half-life — it can remain active in the body for up to 36 hours, earning it the nickname “weekend pill”. Some men take a low daily dose (2.5–5 mg) for continuous readiness.

Drug Facts

Why Shouldn’t You Combine Viagra and Cialis?

It helps to understand the why rather than just hearing don’t.Sildenafil and tadalafil are both PDE5 inhibitors, which means they both relax the blood vessels and increase blood flow to help produce an erection. That’s the same mechanism that makes them effective but it’s also why doubling up is problematic.

Both medicines can lower blood pressure through their effects on blood vessels. When you take two PDE5 inhibitors, you’re not switching to a different system; you’re layering the same effect on top of itself. That can increase the likelihood of unwanted reactions, particularly anything related to blood pressure dropping too far.

It’s also worth resetting a common expectation: more medication does not automatically mean a stronger erection. These drugs have a ceiling effect once the pathway is fully engaged, taking more doesn’t amplify the result, it just raises the risk of side effects. If the first medicine isn’t working, the answer usually lies in how it’s being used or in an underlying cause, not in stacking a second drug.

What Happens When You Take Viagra and Cialis Together?

When both medicines are active in your body at once, the effects can stack up in a few different ways. Here’s what that can look like in practice.

Blood Pressure Can Drop

Because both Viagra and Cialis relax blood vessels, combining them can push blood pressure lower than either would alone. That can lead to:

• Dizziness
• Lightheadedness
• Fainting
• Generalised weakness

For most people these effects are uncomfortable rather than dangerous, but a significant drop in blood pressure can be serious especially if you have a heart condition or take other blood pressure medicines.

Side Effects May Become More Noticeable

Each medicine on its own has a known list of common side effects. Take them together and those effects can become more frequent or more intense, including:

• Headache
• Flushing (warmth and redness in the face or skin)
• Nasal congestion
• Palpitations (a fast or pounding heartbeat)

You can also review the common precautions and adverse effects associated with tadalafil in our guide to Cialis side effects.

Serious Reactions Are Possible

While rare, combining PDE5 inhibitors raises the chance of the more serious reactions associated with these medicines. These need urgent medical attention and include:

• A prolonged or painful erection (priapism)
• Sudden vision changes, including vision loss in one or both eyes
• Sudden hearing changes, including hearing loss or ringing in the ears
• Serious cardiovascular symptoms such as chest pain or a severe drop in blood pressure

If any of these occur, treat it as an emergency and seek medical help immediately.

Can You Take Viagra After Cialis?

This is one of the most common questions people ask: I took Cialis earlier today, can I take Viagra now? The short answer is that it’s not something to do on your own initiative. Tadalafil (Cialis) lasts considerably longer than sildenafil (Viagra) and can remain active for up to 36 hours, so Cialis may still be working in your system when you consider taking Viagra later that day or even the next.

A few hours passing doesn’t automatically mean the medicines no longer overlap, and there isn’t one universal waiting period that’s safe for everyone. To stay safe:

• Treat both medicines as still active in your system until a clinician tells you otherwise.
• Don’t assume a few hours means the overlap is over.
• Discuss any switch from Cialis to Viagra with a healthcare professional for proper spacing and dosing.

Can You Take Cialis After Viagra?

The reverse works the same way in principle. Sildenafil has a shorter duration than tadalafil, typically active for around 4 to 6 hours. If you take Cialis while sildenafil is still in your system, the two can overlap and create the same stacking of PDE5 effects we’ve already covered.

Don’t use Cialis as an extra dose or a quick fix because Viagra didn’t deliver the expected result. A second PDE5 inhibitor won’t necessarily fix the problem, and it does increase the risk of side effects. Instead:

• Talk to a healthcare professional about why the first medicine didn’t work.
• Ask whether switching, with the right spacing, is appropriate for you.

What If Viagra Isn’t Working?

If Viagra does not seem to be working properly, there may be several reasons. It does not necessarily mean that you need a stronger medicine or a second ED tablet.

Possible factors include:

• Taking sildenafil too close to a heavy meal
• Not allowing enough time for the medicine to take effect
• Insufficient sexual stimulation
• Drinking a significant amount of alcohol
• Other medicines affecting erectile function
• Stress or performance-related factors
• Underlying health conditions
• An unsuitable treatment or dose

The way you take sildenafil can also affect how quickly it is absorbed. A heavy meal, particularly one high in fat, may delay its absorption. If you’re unsure about the best way to take it, see our guide on how to take Viagra.

Rather than adding Cialis, speak with a healthcare professional about the lack of response.

They may review your current treatment, consider whether a dose adjustment is appropriate, check for medicine interactions or discuss whether another ED treatment could be more suitable.

Viagra vs Cialis: What’s the Difference?

Although Viagra and Cialis work in a similar way, they are not identical medicines.

Neither is universally “better” than the other. The right choice depends on the individual how often you want spontaneity, how your body responds, any other medicines you take, and what you and your clinician decide fits your life best.

What If You Accidentally Take Viagra and Cialis Together?

Accidents happen maybe you forgot you’d already taken one, or mixed up two prescriptions. Here’s how to handle it.

If you feel well:

• Don’t take another ED medicine.
• Don’t take any additional doses.
• Contact a doctor or pharmacist for individual advice even if you feel fine, it’s worth a quick check-in.
• Keep track of exactly what you took, including the strength and the timing, so you can tell a clinician precisely what happened.

Medicines That Can Make the Combination More Dangerous

Certain other medicines can amplify the risks of taking PDE5 inhibitors and especially of combining them. This isn’t an exhaustive interaction list, but these are the key ones to be aware of. If you take sildenafil regularly, it’s also worth reviewing sildenafil interactions before changing your ED treatment.

Nitrates

Nitrates are the most important ones to know about. They’re commonly used for chest pain (angina) and heart conditions, and they also lower blood pressure. Taking a PDE5 inhibitor with a nitrate can cause a dangerous, potentially life-threatening drop in blood pressure. Examples include:

• Nitroglycerin (also called glyceryl trinitrate / GTN)
• Isosorbide medicines (isosorbide mononitrate and isosorbide dinitrate)

Riociguat

Riociguat is a medicine used for pulmonary arterial hypertension. It also lowers blood pressure, and combining it with PDE5 inhibitors is not recommended because of the added risk.

Some Alpha-Blockers and Blood Pressure Medicines

Alpha-blockers (often used for prostate problems or high blood pressure) and certain other blood pressure medicines can further lower blood pressure. When taken alongside PDE5 inhibitors and especially alongside a combination of them the blood-pressure-lowering effect can add up. This is why it’s so important to give your doctor the full list of everything you take.

What Should You Do Instead of Combining Viagra and Cialis?

If one ED medicine isn’t giving you the results you want, there’s a much safer path than combining two. Different ED pills work in slightly different ways and may suit different people depending on their health, other medicines, and treatment goals. Here’s the practical, doctor-supported approach:

• Review how the current medicine is being used timing, food, alcohol, and stimulation all matter.
• Discuss a dose adjustment with a healthcare professional sometimes a different dose makes all the difference.
• Consider switching from one PDE5 inhibitor to another if sildenafil doesn’t suit you, tadalafil might, and vice versa.
• Review other medicines you take something else may be interfering with your ED treatment.
• Address lifestyle factors smoking, alcohol, weight, stress, sleep, and exercise all influence erectile function.
• Investigate underlying health conditions if ED persists persistent ED can be an early sign of cardiovascular issues, diabetes, or hormonal imbalances that deserve attention in their own right.

Important: don’t increase your Viagra and Cialis dose yourself, and don’t add a second medicine on your own. Any change to dose or treatment should come from a conversation with your clinician.

Key Safety Points of Viagra and Cialis