Cialis vs Viagra: Which ED Medication Is Right for You?

Both Cialis and Viagra are effective treatments for erectile dysfunction, and for most men they work well. The question isn't really which one is better in absolute terms. It's which one suits your lifestyle. The biggest practical difference is how long they last: sildenafil (the active ingredient in Viagra) works for around four to five hours, while tadalafil (the active ingredient in Cialis) can last up to 36 hours. That single fact shapes everything else about how you use them.

This guide covers both medications in plain terms, including how they work, which acts faster, how food and alcohol affect them, side effects, dosage options, and what things actually cost in the UK.

How They Both Work#

Sildenafil and tadalafil belong to the same class of drugs, called PDE5 inhibitors. During sexual arousal, the body releases nitric oxide, which triggers a cascade that relaxes the smooth muscle in the walls of the blood vessels supplying the penis. This allows blood to flow in and an erection to form. PDE5 is an enzyme that breaks down this process prematurely in men with ED. Both sildenafil and tadalafil block PDE5, helping the erection process work as it should.

Neither drug causes an erection on its own. Sexual stimulation is still needed. What these medications do is make the normal physiological process easier to complete when ED has been getting in the way.

Sildenafil (Viagra)#

Sildenafil was originally developed in the late 1980s as a treatment for angina. During clinical trials, researchers noticed a consistent and rather useful side effect: it significantly improved erections. The drug was repurposed and approved as an ED treatment in 1998 under the Viagra brand.

Today, sildenafil is widely available as a generic medication, which makes it considerably more affordable than the original branded version. In the UK, Viagra Connect (sildenafil 50mg) has been available over the counter at pharmacies since 2018, without a prescription, making it the first oral ED treatment to become available OTC in this country. Higher doses (100mg) still require a prescription.

Typically, sildenafil is taken 30 to 60 minutes before sexual activity. Effects usually last four to five hours, though this varies between individuals. The standard starting dose is 50mg, which can be adjusted up to 100mg or down to 25mg depending on how well it works and how well it's tolerated.

Tadalafil (Cialis)#

Tadalafil arrived on the market in 2003 and quickly earned the nickname "the weekend pill" because a single dose can remain effective for up to 36 hours. This longer window is the main reason many men prefer it: you can take it on a Friday evening and not need to think about timing again until Sunday.

Like sildenafil, tadalafil is now widely available as a generic. In the UK, Cialis Together (tadalafil 10mg) became available over the counter in 2024, following a similar regulatory pathway to Viagra Connect.

Tadalafil also has a unique option that sildenafil doesn't: a daily low-dose version. Taking 2.5mg or 5mg every day keeps a low level of the drug in your system continuously, so you don't need to plan around tablets at all. This approach suits men who have sex more than twice a week, or those who simply don't want any connection between taking a pill and having sex.

Which Works Faster?#

Sildenafil generally acts slightly faster. Most men notice effects within 30 to 60 minutes of taking it. Tadalafil typically takes 30 minutes to two hours, though in practice many men find it working within an hour.

The key practical point: neither medication should be taken five minutes before you need it. Both benefit from a bit of forward planning, though tadalafil's long duration means the planning window is far more generous.

High-fat meals slow sildenafil's absorption noticeably. A fatty meal before taking sildenafil can delay onset by up to an hour and reduce peak concentration in the blood. Tadalafil is much less affected by food. You can take it with or without a meal and expect a fairly predictable result either way.

Food, Alcohol and Spontaneity#

Alcohol is worth addressing directly because it's a common question. Both medications can cause a drop in blood pressure, and alcohol does the same. Combining the two isn't dangerous in moderate amounts for most healthy men, but drinking heavily before relying on either medication is a bad idea. Alcohol also impairs sexual response independently, so a large amount of alcohol will often undermine the medication regardless of which one you take.

On the subject of spontaneity: this is often the emotional crux of the decision. Sildenafil requires you to take it roughly an hour before sex. For some men that's fine. For others, the planning element feels clinical and uncomfortable. Tadalafil's 36-hour window largely removes that issue. Daily tadalafil removes it entirely. If spontaneity matters to you, that's a strong reason to consider tadalafil.

You can read more about the full range of ED treatments available in the UK, including both sildenafil and tadalafil options, on Totiva's ED service page.

Side Effects: Sildenafil vs Tadalafil#

Both medications share a similar side effect profile because they work through the same mechanism. The most common side effects with either drug include:

• Headache
• Facial flushing
• Nasal congestion
• Indigestion
• Dizziness
• Temporary changes in vision (more associated with sildenafil)

Tadalafil has a higher incidence of muscle aches and back pain, thought to be due to its inhibition of PDE11 (a closely related enzyme found in muscle tissue) in addition to PDE5. This usually resolves within 48 hours and isn't a sign of anything serious.

Sildenafil's visual side effects, including a bluish tinge to vision or increased light sensitivity, are caused by mild inhibition of PDE6 in the retina. They're temporary and usually mild, but men with existing retinal conditions should discuss this with a clinician before using sildenafil.

Both drugs are contraindicated with nitrate medications (commonly prescribed for angina and heart conditions). The combination can cause a severe and dangerous drop in blood pressure. This is one reason a proper clinical assessment matters before starting either medication.

Dosage Options at a Glance#

Here's a practical summary of what's available:

Sildenafil (as-needed)

• 25mg, 50mg, 100mg tablets
• Taken 30 to 60 minutes before sex
• Effective for around four to five hours

Tadalafil (as-needed)

• 10mg or 20mg tablets
• Taken 30 minutes to two hours before sex
• Effective for up to 36 hours

Daily tadalafil

• 2.5mg or 5mg tablets
• Taken every day, same time
• No planning around sex required

The daily option is particularly popular with men who have sex more than a couple of times a week, or those managing underlying conditions like benign prostatic hyperplasia (BPH), for which daily tadalafil 5mg is also licensed.

What Do They Cost in the UK?#

Cost is often a deciding factor, and the good news is that generics have made both medications very affordable.

Through Totiva, current prices are:

Sildenafil (generic Viagra):

• 50mg, 4 tablets: £4.99
• 50mg, 8 tablets: £9.99
• 100mg, 4 tablets: £6.99
• 100mg, 8 tablets: £11.99

As-needed tadalafil (generic Cialis):

• 10mg, 4 tablets: £7.49
• 10mg, 8 tablets: £12.99
• 20mg, 4 tablets: £8.49
• 20mg, 8 tablets: £14.99

Daily tadalafil:

• 2.5mg, 28 tablets: £9.99
• 5mg, 28 tablets: £14.99

Branded OTC options:

• Viagra Connect 50mg, 4 tablets: £11.99
• Viagra Connect 50mg, 8 tablets: £19.99
• Cialis Together 10mg, 4 tablets: £14.99
• Cialis Together 10mg, 8 tablets: £24.99

For context, if you're in England and eligible for an NHS prescription for sildenafil, you'd pay the standard prescription charge of £9.90 per item. In Scotland and Wales, NHS prescriptions are free of charge, so if you qualify it's worth exploring this route through your GP. Sildenafil has been available on the NHS for erectile dysfunction since 2014, though there are some prescribing criteria that your GP will assess.

For men who don't want to visit a GP or who prefer the convenience of an online pharmacy, Totiva's consultation is free. You only pay once a clinician has reviewed and approved your treatment.

Daily Tadalafil: Worth Considering Separately#

The daily dose option deserves its own mention because it's genuinely different from the on-demand approach. Rather than timing a tablet around sex, you take a small dose every day and maintain a consistent level in your system.

Many men find this psychologically liberating. There's no pill-taking ritual associated with sex, and erections tend to improve steadily over time as the medication builds up. Some research also suggests that daily tadalafil may have benefits for prostate symptoms in men with both ED and BPH.

The trade-off is cost and commitment. You're taking a tablet every day regardless of sexual activity. But at around 36p per day with daily tadalafil 2.5mg from Totiva, many men find it a reasonable exchange for genuine spontaneity.

Which Should You Choose?#

There's no single right answer, and any pharmacy or clinic telling you otherwise isn't giving you the full picture. Here's a rough guide based on what tends to suit different situations:

Consider sildenafil if:

• Cost is a priority and you want the most affordable option
• You don't mind timing around sex
• You have sex less frequently and an on-demand option suits your routine
• You want an over-the-counter option without a prescription (Viagra Connect 50mg)

Consider as-needed tadalafil if:

• Spontaneity matters and you want a wider window of flexibility
• You find sildenafil's four-hour window too limiting
• You want to take medication the night before without worrying about timing

Consider daily tadalafil if:

• You have sex frequently (more than twice a week)
• You want to remove any connection between pill-taking and sex
• You also have urinary symptoms related to an enlarged prostate

A Totiva prescriber can help you work through these options during your consultation, taking into account your health history, any medications you're already on, and your preferences.

Are There Other Options?#

Sildenafil and tadalafil are the most commonly prescribed ED medications in the UK, but they're not the only ones. Vardenafil (Levitra) and avanafil (Spedra) are also licensed in the UK. Spedra in particular has a fast onset (as little as 15 minutes) that some men find appealing. These alternatives are worth knowing about if you've tried both sildenafil and tadalafil without success or with intolerable side effects.

It's also worth acknowledging that ED can have underlying causes, from cardiovascular disease and diabetes to psychological factors and medication side effects. If you're experiencing ED and haven't spoken to a clinician about it, that conversation is worth having. ED can sometimes be an early indicator of cardiovascular risk, and a proper assessment can be valuable beyond just getting a prescription.

A Note on Safety and Buying Online#

Buying ED medication online is legal and convenient in the UK, provided you use a GPhC-registered pharmacy. Totiva is registered with the General Pharmaceutical Council (registration 9012997), which means it operates under the same regulatory standards as your high street pharmacist.

Be cautious about unlicensed websites or products like Kamagra, which aren't licensed for sale in the UK and may contain unknown or inconsistent amounts of active ingredient. The MHRA regularly issues warnings about counterfeit ED medication sold online.

If you'd like to explore your options with a proper clinical consultation, Totiva's online ED service is free to start. You answer a short clinical questionnaire, a UK-registered pharmacist reviews your answers, and you only pay if treatment is approved and suitable for you.