Medical Review by Jennie Stanford, MD, FAAFP, DipABOM
Summary:
- Viagra® and Cialis® both work by inhibiting the enzyme PDE5, which increases blood flow to the penis. The main practical difference between these medications is the amount of time they last for in the body.
- Viagra® is effective for about 4 hours, while Cialis® can last up to 36 hours. Viagra® typically exits the body after 24 hours, whereas Cialis® can remain present for up to 72 hours.
- Combining Viagra® and Cialis® can lead to risks like priapism and lowered blood pressure (which can increase the risk of a heart attack or stroke). It’s best to avoid taking one medication until you know the other is safely out of your system.
- For safe use and appropriate dosages, consulting healthcare providers is essential, especially for those with pre-existing health conditions. Lemonaid Health can connect you with an online doctor based in the US to determine if ED treatment is right for you.
Using Viagra® & Cialis® at the same time
Although Viagra® and Cialis® are both used for treating erectile dysfunction, they both use different active ingredients. Because of this, the temptation may exist for some people to use both medications at once in an attempt to “double” the effects—but does this actually work, and is it safe?
Find out below about how long the different drugs in both of these medications remain in your system, whether they can interact in unexpected ways, and whether you can gain any benefits from taking them both at once. Our team is dedicated to helping you gain the knowledge you need to make better decisions about your health.
How Viagra® (Sildenafil) works
Viagra® (generically known as sildenafil) relaxes the muscles in the penis and allows for increased blood flow during sexual stimulation, which makes it easier to achieve an erection.
Here’s how sildenafil helps the muscles in the penis relax:
- Many men with erectile dysfunction often struggle to produce cyclic guanosine monophosphate (cGMP)—a molecule that helps the muscles in the penis relax so that more blood can flow to them.
- An enzyme called phosphodiesterase type 5 (PDE5) is responsible for breaking down cGMP. When there’s not enough cGMP, this happens too fast and makes an erection difficult to achieve.
- Sildenafil inhibits PDE5 so that cGMP cannot be broken down as fast—making erections easier for men who struggle to produce it.
Frequently asked questions about Viagra®
How long does it take for Viagra® to become active?
You should start to notice Viagra® effects in the body 30-60 minutes after you take it, and should be able to achieve an erection for the next 4 hours or so.
How long does Viagra® last in the body?
The level of Viagra® in your system gradually decreases once you take it. It takes about 4 hours to reach low levels, and up to 24 before it’s completely out of your system.
How much Viagra® should you take at once?
Viagra® comes in tablets with three different strength levels: 25mg, 50mg, and 100mg.
The amount of Viagra® you take should be prescribed by your doctor, and will depend on:
- Your age
- Your health history
- Whether you are taking other medications
Does Viagra® have any known side effects?
The side effects of Viagra® can range from mild to serious, and include:
Mild side effects
- Headache
- Flushing
- Upset stomach
- Abnormal vision, including changes in color vision (having a blue color tinge) and blurred vision
- Stuffy or runny nose
- Back pain
- Muscle pain
- Nausea
- Dizziness
- Rash
Serious side effects
- Priapism (a persistent and painful erection that lasts over 4 hours)
- Sudden vision loss in one or both eyes (generally reported by people taking more than the recommended dose of Viagra® and resolved by ceasing treatment).
- A sudden partial or total loss of hearing (also resolved in most cases when patients stop taking the drug).
These serious side effects are rarely reported. Additionally, there have been some instances of men who have experienced heart attacks, stroke, irregular heartbeats, and death while taking Viagra®—but nearly all of these men have had pre-existing heart problems prior to taking Viagra®, and it is unknown whether Viagra® played a direct role in causing these events.
How Cialis® (Tadalafil) works
Cialis® (known generically as tadalafil), functions similarly to Viagra® by relaxing the muscles in the penis, enhancing blood flow during sexual arousal and facilitating an erection.
Here’s the essential science behind how Cialis® functions:
- Like Viagra®, Cialis® also inhibits PDE5 so that cGMP cannot be broken down too quickly in men that do not produce enough of it.
- This allows the blood vessels in the penis to relax, promoting blood flow to the penile area and making erections easier to achieve.
- The main practical difference between tadalafil and sildenafil is that tadalafil stays in the body for much longer—from 36 hours to as much as 72 hours in some cases.
Frequently asked questions about Cialis®
How long does it take for Cialis® to become active?
Cialis® generally begins to work within 30 minutes to 2 hours after intake.
How long does Cialis® last in the body?
Cialis® can continue to be effective for as long as 36 hours after intake. For this reason, it’s sometimes referred to as “the weekend pill”.
How much Cialis® should you take at once?
Cialis® pills are available in four different strengths: 2.5mg, 5mg, 10mg, and 20mg. There are two ways to take Cialis® for erectile dysfunction: either daily, or on an as-needed basis.
Most patients taking Cialis® for erectile dysfunction on a daily basis start at 2.5mg to 5mg.
Patients taking Cialis® on an as-needed basis can go up to 20mg per day. The appropriate dosage should be determined by a healthcare provider, considering factors like:
- Your age
- Your health history
- Whether you are taking other medications
Does Cialis® have any known side effects?
Like Viagra®, the side effects of Cialis® can be mild or severe. The most common symptoms are mild and generally go away after a few hours or less.
Mild side effects
- Headache
- Indigestion
- Back pain
- Muscle aches
- Flushing
- Stuffy or runny nose
Back pain and muscle aches resulting from Cialis® typically appear after 12-24 hours and go away in under 2 days.
Serious side effects
- Priapism
- Color vision changes (like seeing a blue-ish tinge on objects or struggling to distinguish between blue and green)
- A sudden decrease or loss of vision in one or both eyes (typically resolved once Cialis® is no longer being taken)
- Sudden partial or complete hearing loss (possibly accompanied by ringing ears or dizziness and typically resolved when Cialis® is no longer being taken)
Cialis® is not definitively linked to these side effects, which have only been reported in rare cases and could potentially result from other medications or health conditions as well. If you experience any of the above, consult a healthcare provider immediately.
Potential risks of combining Viagra® & Cialis®
Although sildenafil and tadalafil are different drugs that both block PDE5, they do not complement each other. In fact, taking too many PDE5 inhibitors at the same time can have numerous adverse effects. The patient information for both Viagra® and Cialis® explicitly warm against taking either drug with other erectile dysfunction medications.
Recommendations & precautions
Be sure to tell your healthcare provider about all medication you are taking before seeking a prescription for erectile dysfunction treatment.
Taking Viagra® and Cialis® at the same time can be dangerous. Always consult your healthcare provider before combining medications.
If you feel that the dose of Viagra® or Cialis® you are currently taking is not strong enough, consult a qualified healthcare practitioner. They may be able to prescribe a higher dosage depending on your health history and risk factors.
Consult with our online medical team
When taking medications of any kind, it’s vital to follow the instructions of healthcare professionals for optimal safety and efficacy. Seeking advice from a doctor before taking Viagra® or Cialis® gives you the best chance of increasing the medication’s benefits while reducing the risk of side effects or unwelcome drug interactions.
Learn about erectile dysfunction treatments available with Lemonaid Health.
Viagra® is a registered trademark of Pfizer Inc. Cialis® is a registered trademark of Lilly ICOS LLC.
