Written by Sven Wombwell
Published October 13, 2023 10 minutes read
Last updated:
Cialis® is a brand name for tadalafil, and Viagra® is a brand name for sildenafil. This article compares the medicines and explains their FDA-approved generic tablet options. References to the brands do not mean Male Excel supplies branded products.
Cialis vs Viagra: quick answer
Cialis and Viagra are similarly effective for erectile dysfunction. The main difference is how long they work and when you take them. [1–3]
- Cialis (tadalafil): As-needed doses can work for up to 36 hours. A lower-dose daily option is also available.
- Viagra (sildenafil): Taken as needed, usually about an hour before sex, with effects typically lasting several hours.
- Generic options: Both are available as FDA-approved generic tablets, which generally cost less than the brands. [8]
- Which is better? The right choice depends on your health, other medications, preferred timing and response to treatment.
- Key safety point: Both require sexual stimulation. Never take either with nitrates or "poppers," and do not combine them. [1,2,4,5]
Is Cialis better than Viagra for erectile dysfunction?
Both work well, and head-to-head studies show similar overall effectiveness. What differs is how each one fits your life. Studies also vary in dose, participants and outcome measures, so no single success rate can predict which will work better for you. [3]
That puts the decision in practical terms you already know: whether you want daily treatment or an as-needed pill, how much spontaneity matters to you and which side effects you tolerate best.
| Feature | Cialis (tadalafil) | Viagra (sildenafil) |
| When to take it | As needed: at least 30 minutes before sex; timing varies | Usually about 1 hour before sex; may be taken 30 minutes to 4 hours beforehand |
| Window of effect | Up to 36 hours with as-needed use | Typically effective for several hours; response diminishes over time |
| Food interactions | Can be taken with or without food | A high-fat meal can delay onset |
| Daily option | Yes, a lower-dose daily regimen for ED | No FDA-approved daily ED regimen |
| Side effects | Headache, indigestion, flushing and nasal congestion; back or muscle pain can occur | Headache, flushing, indigestion and nasal congestion; visual changes can occur |
Table sources: [1,2,4,5]
How do Cialis and Viagra work?
Both are phosphodiesterase type 5 (PDE5) inhibitors. They improve blood flow to the penis when you are sexually aroused, helping you get and keep an erection. Both need sexual stimulation to work. They do not increase desire on their own, and a longer window of effect means a longer window to respond, not a continuous erection. [4,5]
Which works faster and lasts longer?
Tadalafil offers a longer window of effect than sildenafil. One as-needed dose can work for up to 36 hours. It can be taken with or without food. Tadalafil can start working within about 30 minutes, and blood levels typically peak around 2 hours after a dose. [1,4]
Sildenafil fits men who prefer a shorter window. It is usually taken about an hour before sex, and a high-fat meal can delay its onset. The timing in the table is a planning guide, not a guaranteed start time. [2,5]
Daily vs on-demand Cialis
Daily and on-demand Cialis contain the same active ingredient, tadalafil. The difference is the prescribed dose and schedule. Both regimens are also available as generic tadalafil. [1,8]
Daily tadalafil: Take a lower dose at about the same time every day, whether or not you plan to have sex. The usual U.S. starting dose for ED is 2.5 mg, which a prescriber may increase to 5 mg. The daily regimen does not require taking a dose specifically before sex. With daily dosing, tadalafil reaches steady levels in the blood within about five days. [1]
On-demand tadalafil: Take it when needed, at least 30 minutes before anticipated sex. The usual starting dose is 10 mg, which a prescriber may adjust to 5 mg or 20 mg. Its effects may last up to 36 hours, giving you a longer window to respond to sexual stimulation. [1,4]
These are general label doses, not personal dosing instructions. Do not add an on-demand dose to daily tadalafil or switch schedules without your prescriber's guidance. [1,4]
Does Cialis make you harder than Viagra?
Head-to-head research found similar overall improvements in erectile function with both. Cialis lasts longer, but that describes how long you can respond to stimulation, not how firm your erection will be. [1–3]
Which is better with testosterone replacement therapy?
If you have ED and confirmed testosterone deficiency, treating both may work better than an ED medication alone. Clinical guidelines advise that in men with ED and confirmed testosterone deficiency, a PDE5 inhibitor may be more effective when combined with testosterone therapy. The guidance applies to both medications, so the choice between Cialis and Viagra still comes down to your health, your other medications and how you respond. [6]
Low testosterone is diagnosed through a clinical assessment and blood testing, not ED symptoms alone. Testosterone therapy is not a general treatment for ED in men with normal testosterone levels. Finding out what is behind your symptoms is the right starting point. [6,7]
What doses are used for erectile dysfunction?
These are general U.S. label doses, not personal dosing instructions. [1,2]
Tadalafil doses depend on whether it is prescribed daily or on demand, as explained above. Your provider chooses the regimen and dose based on your health, other medications, response and side effects. [1]
As-needed sildenafil: The usual dose is 50 mg. Your prescriber may lower it to 25 mg or raise it to 100 mg.
For most men, the maximum is one dose per day. Some health conditions and medications call for a lower dose or longer gap between doses. Follow your prescription, and check with your prescriber before changing your dose or adding another ED medication. [1,2]
What side effects should you know about?
The most common side effects for both are listed in the table above. Back or muscle pain is associated with tadalafil, and visual changes such as a blue tint or blurred vision are associated with sildenafil. If a side effect bothers you or does not go away, tell your provider, who can adjust your dose or medication if needed. [1,2,4,5]
When to seek urgent help
Get emergency care for an erection lasting four hours or longer, even if it is not painful. This is called priapism and can cause permanent damage if left untreated. Stop the medication and get immediate care for sudden vision loss or a sudden drop in hearing. [1,2]
Who should not take Cialis or Viagra?
Why can't you take Cialis or Viagra with nitrates?
Nitrates, such as nitroglycerin and isosorbide, are medicines used for angina (chest pain). Both nitrates and ED medications widen blood vessels. Taking them together can make your blood pressure fall dangerously low. If you take nitrates, even occasionally, you must not take Cialis or Viagra. This warning also applies to recreational nitrites known as "poppers." [1,2]
Do not try to avoid the interaction by spacing out doses yourself. If you take either ED medication and develop chest pain during sex, stop and call 911. Do not take a nitrate to treat the pain. Tell emergency staff which ED medication you took and when you last took it. [1,2,4,5]
Other medications and health conditions to discuss
Riociguat (Adempas) treats certain types of high blood pressure in the lungs. Do not take it with Cialis or Viagra, because the combination can cause a dangerous drop in blood pressure. [1,2]
You should also avoid any ED medication that has previously caused you an allergic reaction, including a reaction to any of its ingredients. [1,2]
Your provider needs to assess whether treatment and sexual activity are appropriate for you, especially if you have heart disease, a recent heart attack or stroke, blood pressure problems, kidney or liver disease, or certain eye conditions. [1,2]
Alpha-blockers, used for high blood pressure or prostate symptoms, can add to the blood-pressure-lowering effect of either medication. Your provider will typically want your alpha-blocker dose to be stable first and may start you on a lower ED medication dose. [1,2]
Other medications that may require dose adjustments or extra caution include blood pressure medicines, antifungals, HIV protease inhibitors and certain seizure medications. [4,5]
Herbal supplements can interact with ED medications too. Tell your provider about all supplements and herbal products you take, including St. John's wort, and check before starting or stopping them. [4,5]
Why avoid grapefruit with Cialis or Viagra?
What you eat and drink can also affect your medication. Grapefruit and grapefruit juice can slow the breakdown of Cialis and Viagra, potentially increasing the amount of medication in your bloodstream and the risk of side effects. Research has shown this effect with sildenafil (Viagra), and prescribing information for tadalafil (Cialis) warns that grapefruit may increase tadalafil levels. [1,9,10]
For this reason, avoid grapefruit and grapefruit juice unless your prescriber or pharmacist confirms they are appropriate with your prescription. Using grapefruit to try to make either medication stronger is not safe. [4,5,9,10]
What about alcohol?
Alcohol is another part of your routine to discuss with your provider. Heavy drinking can make erections harder to get, and substantial alcohol intake with tadalafil can increase dizziness and the risk of low blood pressure. Ask your provider how much alcohol, if any, is appropriate for you while taking your prescribed medication. [1,7]
Are generic tadalafil and sildenafil different from Cialis and Viagra?
Cialis is the brand name for tadalafil; Viagra is the brand name for sildenafil. The terms "generic Cialis" and "generic Viagra" commonly refer to generic tadalafil and generic sildenafil, respectively. These are generic medicines, not the branded products. FDA-approved generics contain the same active ingredient and must meet FDA requirements for equivalence to their brand-name counterparts. They generally cost less. They may differ in appearance or inactive ingredients. [8]
This comparison covers FDA-approved tablets only. It does not apply to compounded ED medications.
Which costs less?
Generic versions of both generally cost less than the brands. [8] Beyond that, the lower price depends on your plan. A daily prescription and a few as-needed tablets are different purchases, so compare the total monthly cost of your prescribed dose, including consultation, shipping and ongoing care.
Frequently asked questions
Can you take Cialis and Viagra together?
No. Taking two PDE5 inhibitors together can increase risks, including low blood pressure. If you want to switch, ask your prescriber how to do it safely without overlapping doses. [1,2]
Does daily Cialis mean you are always ready?
Daily tadalafil does not require taking a dose specifically before sex. Take it at about the same time each day as prescribed. You still need sexual stimulation for it to work, and it does not increase desire. [1,4]
What if the medication does not work?
Talk with your provider before changing anything. Timing, how you take it and underlying health issues all affect results, and a dose adjustment or a different ED treatment may work better for you. [7]
Explore ED treatment with Male Excel
Whether you prefer daily treatment or an as-needed option, Male Excel offers generic tadalafil, including a daily tadalafil option, and generic sildenafil. These are generic medicines, not branded Cialis or Viagra. A licensed medical provider reviews your health history and medications to determine whether treatment is appropriate and which option and dose may suit you.
How online ED treatment works
- Complete an online assessment. Share your symptoms, medical history and the medications you take.
- Have your information reviewed. A licensed provider assesses whether ED medication is appropriate for you and prescribes treatment when clinically suitable. An online consultation may also be required.
- Receive discreet delivery. If prescribed, your medication is shipped to your door in discreet packaging.
Male Excel requires a physical examination with vitals taken by a provider within the past three years for online ED prescribing.
Prescription treatment is subject to a provider's evaluation. Results vary. This article is for general information and does not replace medical advice. Review the medication's full prescribing information and discuss benefits, risks and interactions with your provider.
Cialis® and Viagra® are registered trademarks of their respective owners. The brand names are used for identification and comparison.
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