Cialis vs Viagra: The key differences

Reviewed by Dr Bhavini Shah

Although Viagra is the most well-known medication for erectile dysfunction, several alternative treatments are available including Cialis. Both treatments can help men achieve satisfying erections and beat erectile dysfunction. However they have differing characteristics which will suit different men in different ways. In this article, we'll look at:

• Active ingredients and effectiveness: Cialis contains tadalafil, while Viagra contains sildenafil. Both medications are effective for treating erectile dysfunction, but they differ in how quickly they work and how long their effects last.
• Usage and Dosage: Cialis can be taken daily or as needed, with effects lasting up to 36 hours. Viagra is typically taken as needed, about an hour before sexual activity, with effects lasting around 4.
• Side Effects and Availability: Both medications have similar side effects, including headaches and flushing. They are available by prescription, and the choice between them depends on individual needs and medical advice.

How do Cialis and Viagra treat erectile dysfunction?

The main ingredients in Viagra and Cialis, sildenafil and tadalafil, are both PDE-5 inhibitors. This means they relax the smooth muscles in the blood vessels supplying the penis. This relaxation increases blood flow to aid an erection.

Neither Viagra or Cialis will cause an erection on their own. Both drugs require sexual stimulus to take effect.

“There is a chance that either treatment might require multiple tries before working and may not help if the cause of your ED is unrelated to blood flow, i.e. it is due to a psychological factor. Make sure you understand the root of your ED before starting treatment.” - Dr Bhavini Shah

Do Cialis or Viagra treat premature ejaculation?

While Cialis and Viagra help with maintaining and strengthening erections, they are unable to help with other sexual problems like premature ejaculation. While the two issues can be linked, neither Viagra nor Cialis are approved to treat premature ejaculation. Separate premature ejaculation treatments like EMLA cream or Priligy tablets can be prescribed following a consultation.

A clinical study that measured the effect of sildenafil (the active ingredient in Viagra) on PE patients showed that using the treatment had a minimal effect on time until ejaculation. However, the treatment did increase patient confidence and perception of control over ejaculation.

What is the difference between Cialis and Viagra?

The main differences between Cialis and Viagra are:

• Different active ingredients – tadalafil and sildenafil
• Different available dosages
• How long effects last – clinical trials have shown Viagra was effective up to four hours after administration whereas Cialis may still be effective up to 36 hours after taking the tablet
• Viagra is best taken on an empty stomach, Cialis can be taken with or without food

How to take Viagra or Cialis

Cialis is faster-acting than Viagra:

• You can take Cialis as little as 30 minutes before you plan to have sex
• Viagra must be taken at least one hour before sex 

You should take Viagra on an empty stomach. If you have a large meal shortly before taking a pill, it will slow down the rate at which Viagra takes effect. 

In contrast, you can take Cialis before or after eating. With both treatments you should limit your alcohol intake to enjoy the greatest effects.

You may not respond to erectile dysfunction treatment the first time you take it. Don’t be alarmed if nothing happens. You may have to try taking the tablet on multiple different occasions before it starts to work. Do not take multiple tablets – this does not increase the likelihood of Cialis or Viagra working, but may increase the chance of suffering from side effects.

If you don’t see any results, speak to your doctor or message us through your account. You may need to switch to a different dose or form of treatment.

Can you take Cialis and Viagra together?

You should not take Cialis and Viagra together. Taking two ED treatments at once will not increase the likelihood of you getting an erection. This will increase the likelihood of you experiencing side effects, including your blood pressure dropping. Speak to your healthcare provider before starting any treatment.

Is Viagra more effective than Cialis?

Both medications can help men achieve and sustain an erection during sex. Neither one is more ‘powerful’ or can make you harder than the other.

Clinical trials on the active ingredients for Viagra and Cialis – sildenafil and tadalafil – had a near-identical number of patients reporting improved erections (82% and 81% respectively*).

The best treatment for you may depend on how often you have sex. Cialis and Viagra are taken on demand before sex, whereas Cialis Daily is an option for men who have sex three or more times a week. For many men Cialis works faster than Viagra and the effects can last for longer.

*Sildenafil stat is for 100mg dose, compared to 25% reported improvement on placebo. Tadalafil stat is compared to 35% on placebo.

How long do the effects last?

The biggest difference between Viagra and Cialis is the amount of time their effects last:

• Viagra remains effective for 4 to 6 hours, which offers ample opportunity to have sex on multiple occasions if you wish
• Cialis typically allows you to achieve erections for up to 36 hours after taking a tablet

Although Cialis lasts for up to 36 hours, this does not mean you will have an erection throughout that time – it should only happen when you are sexually stimulated. Cialis has comfortably the longest effectiveness period of any erectile dysfunction drug on the market.

Cialis dosage vs Viagra dosage

The dosage of a medicine relates to how much active ingredient it contains. Higher doses tend to have stronger effects. However, the right dosage for you will depend on your own needs and whether you have any health conditions.

Cialis on demand and Viagra are available in the following dosages:

Cialis vs Viagra side effects

As with any medication you may experience side effects when taking Cialis or Viagra. Side effects may be more common in people who take higher doses of ED medication.

If you experience any of the following side effects from taking Cialis or Viagra, stop treatment and seek immediate medical attention:

• Allergic reaction
• Chest pain
• Seizures
• Vision changes
• A prolonged erection

Can you get Cialis and Viagra over the counter?

Cialis and Viagra are prescription-only medicines (POMs) – which, as the name suggests, means they are not available to purchase over the counter and will require a prescription.

Some forms of Cialis and Viagra can be sold over the counter. These include Viagra Connect and Cialis Together, which have different pack sizes and dosages than the ‘standard’ Viagra and Cialis.

Choosing between Cialis and Viagra

It can be hard to know which ED treatment is right for you. There are lots of things to consider if you’re comparing treatments such as:

• Doses
• Duration of effects
• Potential side effects
• When you plan to have sex
• Price
• Any intolerances or allergies to ingredients

Active ingredients

Some men may react better to one active ingredient than the other. Viagra contains the active ingredient sildenafil whereas Cialis contains tadalafil. Both sildenafil and tadalafil work via the same mechanism to help you achieve and keep an erection. However, tadalafil stays in the bloodstream for longer.

Because they work in the same way you should never take the two drugs together. Nor should you take more than one Viagra or Cialis pill at any one time. 

Safety

Side effects for either drug are rare but not unheard of. As Cialis and Viagra are both PDE-5 inhibitors, they have similar side effects. Although you may find that because Cialis is effective for longer, any side effects you experience may also last for longer. The most likely unwanted effects are: 

• Light-headedness
• Headaches
• Flushing to the face

Nasal congestion, indigestion and visual changes are sometimes experienced as well.

If you experience chest pain or a prolonged erection for more than four hours, you must seek urgent medical help. Both Viagra and Cialis are prescription drugs so you must consult with a doctor before you can take them. 

Cost

Cost is another notable distinction between Viagra and Cialis. The longer effectiveness of Cialis is reflected in its price. While Cialis is slightly more expensive than Viagra, many men will consider the vastly greater duration period of Cialis to represent good value for money. Equally, plenty of men will prefer the cheaper price and renowned brand name offered by Viagra. But ultimately it depends entirely on the individual.

Alternative ED treatments

While popular, Viagra and Cialis are only two options for treating erectile dysfunction. There are a range of treatments available on LloydsPharmacy Online Doctor, including tablets, sprays and creams. You can choose a treatment option during a short consultation or discuss options with our experienced clinicians.

There are also alternative treatments for ED including counselling, devices like vacuum pumps or lifestyle changes (i.e. healthier diet or cutting back on alcohol).

Conclusion

Though many people would like to know which treatment is better, there really is no straightforward answer to that question. As we’ve seen Viagra and Cialis have their similarities and differences.

The effectiveness of the treatment varies from one man to another, depending on the cause of the erectile dysfunction, its severity and the amount of sexual stimulation the person receives. Until you try for yourself, you cannot be sure of the exact results you will achieve.