Highlights
- Can you take Cialis and Viagra together? The short answer is no. While Viagra and Cialis are effective separately, they shouldn’t be taken together.
- Taking two different ED drugs at the same time elevates your risks of side effects, including visual disturbances and priapism.
- Always follow the instructions on the bottle. If a drug doesn’t seem to be working, speak with your doctor.
Cialis and Viagra are so effective at treating the symptoms of erectile dysfunction, it’s easy to get carried away and wonder if you’d get even more benefit by taking them together.
Don’t. Taking Cialis and Viagra together is a bad idea and not worth the risk. Instead, choose one or the other, or consult with one of our online doctors to see which one is best for you.
How Do Cialis and Viagra Work?
All oral erectile dysfunction medications block an enzyme called phosphodiesterase-5 (PDE5), which increases blood flow to the penis and results in a harder, longer-lasting erection. To understand how this relates to taking Cialis and Viagra together, it helps to know the basics of how erections happen.
When men get sexually aroused, the nerves near the penis release nitric oxide. Nitric oxide is a chemical signal that tells the cells in the blood vessels of the penis to make more of a substance called cyclic guanosine monophosphate, or cGMP. cGMP makes the blood vessels relax and open up so more blood flows into the penis to make it rigid.
When a guy isn’t aroused anymore, PDE5 acts like a molecular clean-up crew by breaking down the cGMP, which lets blood flow out of the penis so it becomes flaccid again.
In men with ED, the initial arousal signal doesn’t generate enough cGMP to make the penis fully hard and keep it that way long enough to have sex. By blocking PDE5, drugs like Viagra slow the breakdown of cGMP so enough of it accumulates to produce an erection.
There’s No Benefit to Taking Cialis and Viagra Together
Before we even touch on the possible health risks, you should know that taking Viagra and Cialis together isn’t going to give the double-boost you think it will. We mention this first just in case safety issues aren’t enough to deter you from trying!
Viagra and Cialis interfere with PDE5 because they’re shaped like cGMP, one of the molecules that binds with PDE5. These drugs are even better at attaching to PDE5 than cGMP, and they compete against each other for the open binding sites on the enzyme. Once it’s in place, Viagra won’t budge, and every site taken up by Viagra or Cialis is one that can’t bind to cGMP to break it down.
Since there are a limited number of sites, once they’re all full, taking more Viagra isn’t going to have any additional effect. There’s simply no room; it’s already too crowded!
Because both drugs target the same enzyme, taking both together would be similar to taking an overdose of only one of them. Whether occupied by Viagra or Cialis, there’s a point where all the enzyme molecules are saturated, and the extra drug gets carried around your body waiting to be broken down by the liver.
Is It Safe To Take Viagra and Cialis Together?
No, it’s not safe to pair these drugs. PDE5 isn’t only found in the penis; it’s just one of many types of phosphodiesterases. This is where the health risk part comes in.
Phosphodiesterases are a big family of enzymes that break down messenger chemicals like cGMP. They’re used all over the body to give instructions to nearby cells and tissues. Since PDE5i drugs are so similar to cGMP, they can bind to PDE5 found in locations besides the penis, like the retina, large intestine, and blood vessels.
Although ED drugs prefer binding to PDE5, they can also bind to other PDE types. The more excess Viagra in your system, the more likely it is to run into and attach to other PDE enzymes. This unintended activity is thought to be the cause of the most frequently reported side effects of ED drugs: headache, dizziness, temporary visual changes, muscle pain, and stomach upset.
Just like taking too much Viagra by itself, adding a normal dose of Cialis to a normal dose of Viagra increases your chances of side effects from too much of a good thing. This includes a greater risk of visual disturbances, headache, very low blood pressure, and an otherwise rare side effect called priapism, which is a painful erection that doesn’t go away on its own, even when you aren’t sexually stimulated.
You’ve heard the commercials telling you, “Contact your doctor immediately if you have an erection lasting longer than four hours,” right? That’s mentioned separately from the rest of the side effects because priapism can be a medical emergency that needs swift treatment to prevent serious damage to the penis. After four hours, the blood trapped in the erect penis has barely any oxygen left, and unless it’s drained right away so new blood can enter, the cells in the erectile tissue will start to die.
If the idea of inadvertently crippling your penis doesn’t make you think twice about taking Viagra and Cialis together, here’s a full overview of emergency treatment of priapism. If you’re the squeamish type, just take our word for it: It’s pretty horrible.
What To Do If Your ED Medication Isn’t Working
While PDE5 inhibitors are very effective for erectile dysfunction, our bodies are all different and respond to drugs differently. If you’re taking the max dose of your prescribed ED drug and still aren’t experiencing the hoped-for effects, talk with your doctor about trying a different ED drug.
You can take them all for a test drive if your doctor approves, but just like with cars, you can only test drive one at a time. However, Viagra can be safely and effectively used in combination with ED drugs that work by a different mechanism of action, like Caverject or MUSE (Medicated Urethral System for Erections). For maximum effect, you can also combine any of the ED drugs with a male enhancement pump.
Need a more detailed rundown of what you should do when Viagra isn’t doing it for you? We’ve got an article for that.
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Dan is a long-time freelance writer focusing on technology, science, health, and medicine, with a lifelong interest in physics, biology, and medicine. His work has taken a particular focus on scientific studies “beyond the headlines,” reading the study to more closely examine the results.