A Comparison of Cialis vs. Viagra: Which Is Best?
Written byJennifer Williamson, PharmD
Medically Reviewed byJennifer Williamson, PharmD
February 12, 2025 (Updated February 12, 2025)
Cialis and Viagra basics
Both Cialis® and Viagra® are FDA-approved prescription medications that are used to treat erectile dysfunction (ED). ED can occur if you have trouble getting and maintaining an erection. Both Cialis and Viagra are pills that you’d take by mouth and are two of the most common treatment options for ED.
What is Cialis?
Generic drug/active ingredient: tadalafil
Available dosage strengths: 2.5 mg, 5 mg, 10 mg, 20 mg
Drug class: phosphodiesterase type 5 (PDE-5) blocker
Dosage form: oral tablet
Drug uses: erectile dysfunction (ED) and benign prostatic hyperplasia (BPH)
Cialis is an ED medication that’s made by Eli Lilly and was FDA approved in 2003. Cialis can be taken once daily or as needed for sex. Cialis comes in the brand name form and is also available in a generic called tadalafil.
Both Cialis and tadalafil are safe, effective, FDA-approved medications that will help to treat ED. However, tadalafil, the generic form of Cialis, is a more affordable treatment option.
What is Viagra?
Generic drug/active ingredient: sildenafil
Available dosage strengths: 25 mg, 50 mg, 100 mg
Drug class: phosphodiesterase type 5 (PDE-5) blocker
Dosage form: oral tablet
Drug uses: erectile dysfunction (ED)
Viagra is also an ED medication, but it’s made by Pfizer. Viagra has been around longer than Cialis, and was FDA approved in 1998. It is taken as needed for sex. Viagra is available in the brand name form or a generic called sildenafil.
Both Viagra and sildenafil are safe and effective medications that are FDA-approved to treat ED. However, sildenafil (the generic form of Viagra) is the more affordable option.
Read on for more information about additional similarities and differences and a comparison of Cialis vs. Viagra.
Cialis vs. Viagra: How they work
Both Cialis and Viagra are both approved to treat the symptoms of erectile dysfunction (ED). They belong to the same group of drugs, called phosphodiesterase type 5 (PDE-5) blockers. PDE-5 blockers work by blocking an enzyme called PDE-5. Blocking this enzyme causes the muscles of the penis to relax, which allows blood vessels to expand and blood flow into the penis to increase. This allows an erection to occur.
It’s important to note that Cialis and Viagra will only work along with sexual stimulation. These medications do not cause an erection to occur without sexual activity.
Are both Cialis and Viagra effective?
Yes, both Cialis and Viagra are effective erectile dysfunction treatment options that are FDA approved. In clinical trials for both Cialis and Viagra, the drugs showed that they were effective in helping to achieve and maintain an erection. In a study that compared the effectiveness of generic Cialis (tadalafil) and generic Viagra (sildenafil), tadalafil and sildenafil were about equally effective.
Certain medications may work better for certain people. So, your doctor may recommend trying either Cialis or Viagra and seeing which one works best for you.
Does Cialis or Viagra work faster?
It takes about 30 to 60 minutes for either Cialis or Viagra to begin working. However, Viagra reaches its peak (when you have the most medication in your body) about 1 hour after you take your dose. In comparison, Cialis doesn’t reach its peak for about 2 hours after your dose.
The amount of time the medications take to work also depends on how you’re taking them. Viagra is always taken as needed prior to sex. But, Cialis can be taken as needed prior to sex or it can be taken once daily. If you take the drug once daily, it will work as soon as there’s sexual stimulation and you won’t need to take your dose and wait for it to work.
The type of food you eat prior to taking Viagra can also affect how quickly the drug works. If you eat a high fat meal prior to your dose of Viagra, the drug can take longer to work and may not be as effective. So, if you take Viagra on an empty stomach or after a low fat meal, it may work faster than if you take the drug after a fatty meal. Meals do not affect Cialis like they affect Viagra.
Both Cialis and Viagra require sexual activity in order to work. So, these medications will not cause an erection to occur without sexual stimulation.
For more information about Viagra vs. Cialis (or the generic forms sildenafil vs. tadalafil) and which medication may be the best treatment option for you, talk to your doctor.
Which works longer, Viagra or Cialis?
Cialis works longer than Viagra. Cialis can help you to achieve or maintain an erection for up to 36 hours after a dose of medication. In comparison, Viagra can work for only about 4 hours after your dose. Cialis and Viagra both require sexual stimulation to cause an erection.
It’s important to note that exactly how long Cialis or Viagra works in your body may depend on other factors as well, including your age, other medications that you’re taking and other medical conditions that you have. Your doctor will be able to recommend the best treatment option for you and how long it may work for you.
Dosage recommendations for Cialis vs. Viagra
The recommended dosage of Cialis for ED depends on how you’re taking the medication. Cialis can either be taken as needed prior to sex or it can be taken once daily. If you take Cialis prior to sex, your starting dose will likely be 10 mg. This dose may either be increased to 20 mg or decreased to a lower dose of 5 mg depending on how well the drug is working for you. In comparison, if you take a once daily dose of Cialis, your dose will likely be 2.5 mg to 5 mg once daily.
Viagra is only taken as needed prior to sex. This may also be called “on demand”. It’s not recommended to take the drug once daily every day, unless you’re having sex. The recommended starting dose is 50 mg taken 1 hour before sex. However, your dose can be increased to 100 mg or decreased to 25 mg based on how the drug works for you.
Below is a table comparing the recommended doses of Cialis vs. Viagra:
Brand name | How it’s taken | Starting dose | Dosing ranges |
|---|---|---|---|
Cialis | 30-60 minutes prior to sex with or without food | 10 mg | 5 mg - 20 mg |
Once daily with or without food | 2.5 mg - 5 mg | 2.5 mg - 5 mg | |
Viagra | 30-60 minutes prior to sex on an empty stomach or with a low fat meal | 50 mg | 25 mg - 100 mg |
You should always take the dosage of Cialis or Viagra that your doctor prescribes for you. Never take more medication than recommended. More medication or taking higher doses does not always mean that a drug will work better. In most cases, taking a higher dose of Cialis or Viagra may increase your risk of side effects and may not be more effective at treating your ED. If you have additional questions about the best dose of Cialis or Viagra for you, talk to your doctor.
Side effect comparison: Cialis vs. Viagra
Cialis and Viagra both work in similar ways to manage ED symptoms. Because the drugs work in similar ways, they also share many similar side effects. However, the active ingredients of Cialis and Viagra are different, so they may have some differences in side effects as well.
Most side effects of Cialis and Viagra are mild, and go away quickly. However, it’s possible to experience serious side effects from Cialis or Viagra as well. You should be aware of common and serious side effects that may occur, so that you can tell your doctor right away if you experience any.
Both Cialis and Viagra can cause common side effects such as:
- Headache
- Flushing
- Indigestion
- Nasal congestion
- Low blood pressure
- Back and muscle pain
- Nausea
- Dizziness
- Rash
- Allergic reaction
In addition, both Cialis and Viagra can cause more serious side effects, like prolonged erection, priapism, hearing loss or vision loss to occur.
However, Cialis and Viagra also have some different side effects. For example, Viagra can cause vision changes such as blurry vision or light sensitivity. Cialis isn’t known to cause these side effects. In addition, Cialis is known to cause other side effects, like cough, diarrhea, pain in the arms or legs or infection. Viagra isn’t known to cause these side effects to occur.
In addition, side effects of Cialis may last longer than side effects of Viagra. This is because Cialis lasts longer in your body than Viagra does.
Below is a table of the side effects of Cialis vs. Viagra:
Side effect | Cialis | Viagra |
|---|---|---|
headache | x | x |
flushing | x | x |
indigestion | x | x |
back pain | x | x |
Nasal congestion | x | x |
Low blood pressure | x | x |
Prolonged erection or priapism | x | x |
Hearing loss | x | x |
Sudden vision loss | x | x |
Blurry vision | x | |
Light sensitivity | x | |
Allergic reaction | x | x |
cough | x | |
diarrhea | x | |
Pain in the arms or legs | x | |
infections | x | |
Muscle aches | x | x |
For more information about side effects of Viagra or Cialis, talk to your doctor or pharmacist.
Cost difference: Cialis vs. Viagra
Both Cialis and Viagra are available in the brand name form and a generic form. The generic form of Cialis is called tadalafil and the generic Viagra is sildenafil. In general, generic drugs are more affordable than the brand name versions.
In many cases, insurance may not cover the cost of Cialis or Viagra. However, the cost of ED medications, especially the generic versions, may be affordable without insurance. The cost of Cialis and Viagra may depend on many factors including:
- If your insurance covers Cialis or Viagra
- Your dose of Cialis or Viagra
- The number of tablets of Cialis or Viagra that you’re prescribed
- Your pharmacy
- If you receive brand name or generic Cialis or Viagra
Below is a table of the approximate costs of Viagra, generic Viagra, Cialis and generic Cialis at Motivated.com:
| Drug name | Approximate cost |
|---|---|
| Cialis | For daily use: From $18 per pill |
| For as needed use: From $105 per pill | |
| Generic Cialis (tadalafil) | For daily use: From $1 per pill |
| For as needed use: From $3.50 per pill | |
| Viagra | From $110 per pill |
| Generic Viagra (sildenafil) | From $3 per pill |
Motivated is a trusted telehealth service that connects you with doctors and provides delivery of FDA-approved ED medications discreetly to your door. Motivated also provides many other benefits, including free 2-day shipping and 24/7 access to Health Concierge support from US licensed medical professionals. In addition, the process to get ED medications prescribed through Motivated is 100% online, so you don’t have to worry about any awkward in-person doctors visits. For more information about getting ED medications through Motivated, see Motivated.com. For more information about Cialis vs. Viagra or tadalafil vs. sildenafil, talk to your doctor or healthcare provider.
Safety of Cialis and Viagra
For most people, Cialis and Viagra are safe medications to take. In fact, PDE-5 inhibitors like Viagra and Cialis are recommended by the American Urology Association (AUA) for the treatment of ED. These drugs are approved by the Food and Drug Administration (FDA) and have been shown in clinical trials to be safe and effective at managing symptoms of ED.
For some people, Cialis and Viagra may not be safe to take. It’s possible that these medications may be unsafe for people with certain health conditions, like low blood pressure. It may also be unsafe for people taking certain medications, like nitrates, to take Cialis or Viagra. Before starting either Cialis or Viagra, be sure to tell your doctor about any medical conditions that you have and any prescription drugs, over-the-counter drugs or supplements that you take. Your doctor will help discuss Viagra vs. Cialis and determine which is a safe ED treatment option for you.
Drug interactions of Cialis and Viagra
Since Viagra and Cialis work in similar ways to treat ED, their drug interactions are also similar. Certain drugs can interact with Cialis and Viagra. Medications that may interact with Cialis or Viagra include:
- Nitrates for chest pain (also known as angina), like nitroglycerin
- Alpha blockers
- Certain medications for hypertension (high blood pressure)
- Guanylate cyclase stimulators, like riociguat
- Certain medications used to treat bacterial or fungal infections (antibiotics or antifungals)
- Certain HIV treatments
It’s also recommended to avoid excessive amounts of alcohol while taking Cialis or Viagra.
Before you start taking either medication, be sure to tell your doctor about any other medications that you take. They can help determine if Cialis or Viagra is safe for you to take.
Warnings and precautions
Before taking Cialis or Viagra, talk to your doctor about any other medical conditions that you have. Certain medical conditions may increase your risk of side effects occurring and in some cases if you have certain conditions, it may not be safe for you to take CIalis or Viagra. Tell your doctor if you have any of the following conditions before taking Cialis or Viagra:
- Heart problems, such as heart failure or irregular heartbeat
- Stroke or heart attack
- Recent heart surgery
- Hypertension (high blood pressure)
- Hypotension (low blood pressure)
- Certain blood conditions, including sickle cell anemia
- Stomach ulcers
- Eye disease or vision loss
- Kidney or liver problems
- Abnormal penis shape, like Peyronie’s disease
Your doctor can help determine if Cialis or Viagra may be safe for you based on your other medical conditions.
Key differences and similarities: Cialis vs. Viagra
Cialis | Viagra | |
|---|---|---|
Generic name | Tadalafil | Sildenafil |
Indications | Erectile dysfunction or benign prostatic hyperplasia (enlarged prostate) | Erectile dysfunction |
When to take | 30-60 minutes before sex or once daily with or without food | 30-60 minutes before sex on an empty stomach or with a low fat meal |
How long it lasts (duration of action) | Up to 36 hours | Up to 4 hours |
Recommended dosages | 2.5 mg - 5 mg if taken once daily 5 mg - 20 mg if taken as needed prior to sex | 25 mg - 100 mg |
Dosage form | Oral tablet | Oral tablet |
Drug class | PDE-5 inhibitor | PDE-5 inhibitor |
Frequently asked questions
Both Cialis and Viagra are FDA-approved, effective medications used to treat ED. In a study that compared the effectiveness of generic Cialis (tadalafil) and generic Viagra (sildenafil), tadalafil and sildenafil were about equally effective. But, this study also showed that many people preferred tadalafil vs. sildenafil because the drug works for a longer period of time.
Though these medications are equally effective, they do have some differences, such as the dosages and how long they work. Talk to your healthcare provider about the best if you have additional questions about Viagra vs. Cialis or sildenafil vs. tadalafil.
Key Takeaways
- Cialis and its generic, tadalafil, and Viagra and its generic, sildenafil, are FDA approved, effective ED treatments. Cialis and tadalafil are equally safe and effective, and Viagra and sildenafil are also equally safe and effective.
- The generic forms tadalafil and sildenafil are more affordable than the brand name forms. In fact, the generics can be up to 90% cheaper than branded versions!
- Cialis is taken as needed or once daily, but Viagra is only taken as needed.
- Dosing of Cialis is 2.5 to 20 mg, while dosing of Viagra is 25 to 100 mg. Cialis lasts for up to 36 hours, while Viagra lasts for up to 4 hours.
- Cialis and Viagra have some similar and some different side effects, but drug interactions and precautions for both drugs are similar.
- For more information, see your doctor or visit Motivated.com where you can have ED medications delivered discreetly to your door.
This article offers general information and is not intended as medical advice. It does not replace the expertise of a licensed healthcare professional, who should be consulted regarding any medical questions or treatment decisions. Always seek personalized guidance from your doctor before starting or changing any treatment. While efforts are made to ensure accuracy, the content may not address all potential risks, possible uses or benefits.
