What Causes Erectile Dysfunction? Symptoms, Risk Factors, and Treatments Explained
Clara Hanson Smith
Erectile dysfunction (ED) is a common condition affecting over 50% of men between 40 and 70 in the UK…
Tadalafil vs Sildenafil: Which one is right for you?
5 min read time
Written by: Sunny Dhain
Medically reviewed by: Tannaz Sohrabi
Published 15/01/2026
Updated 06/07/2026
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Key takeaways
- Both are PDE5 inhibitors that improve blood flow to the penis, and they only work when you're sexually aroused.
- Sildenafil (Viagra) works in 30–60 minutes and lasts about 4–6 hours.
- Tadalafil (Cialis) takes effect in about 30 minutes, can last up to 36 hours, and is the only one that can be taken as a low daily dose.
- The main difference in side effects is that Sildenafil is more likely to affect vision, while Tadalafil is more likely to cause back or muscle ache.
- Neither is stronger or safer. The right choice depends on your routine, health and any other medicines you take.
Tadalafil and Sildenafil are the two most widely prescribed tablets for erectile dysfunction (ED) in the UK. They work in much the same way, so the practical differences are how quickly they act and how long they last. That’s usually what decides which one suits you. Here’s how they compare, and how to think about the choice.
What’s the difference between Sildenafil and Tadalafil?
Both belong to the same group of medicines, called PDE5 inhibitors, and both relax the blood vessels to the penis to improve blood flow when you’re aroused. Neither produces an erection on its own; you still need sexual stimulation for them to work.
The real difference is timing. Sildenafil reaches peak effect at roughly 1 to 2 hours after taking the dose and wears off after about 4 to 6 hours. Tadalafil takes a similar time to start but can last up to 36 hours, which is why it’s nicknamed the “weekend pill”. Also, Tadalafil can be taken once a day at a low dose, eliminating the need to plan around a tablet.
How to take them
Sildenafil
- Take one tablet about an hour before sex and never more than one in 24 hours
- Works best on an empty stomach; a heavy or fatty meal can delay its effects
Tadalafil
- Take at least 30 minutes before sex
- Take no more than one dose in 24 hours
- Do not take grapefruit juice
Dosages
Sildenafil
- Available as 25mg, 50mg and 100mg tablets, with 50mg being the usual starting dose
Tadalafil
- Usual starting dose is 10mg (adjusted to 5mg or 20mg depending on how you respond)
- It can also be prescribed as a 2.5mg or 5mg daily tablet, taken at the same time each day.
Is Tadalafil stronger than Sildenafil?
Not exactly. At standard doses, both are similarly effective at producing an erection firm enough for sex. In the manufacturers’ studies, Sildenafil worked for about 74% of men at 50mg and 82% at 100mg, while Tadalafil improved erections in roughly 86%, 83%, and 72% of men with mild, moderate, and severe ED, respectively.
Tadalafil is preferred for its long duration of action. A higher dose of Tadalafil, such as 20 mg, will have a stronger effect, but it doesn’t make the medicine last longer.
Is one safer than the other?
Their safety profiles are very similar. Both are well-established and, for most men, well tolerated. Importantly, neither should be taken with nitrates (used for chest pain) or “poppers”, or with each other or other medications used for ED, as the combination can cause a dangerous drop in blood pressure.
Both may also be unsuitable if you have certain heart conditions, very low or uncontrolled blood pressure, or a history of specific types of vision loss.
What matters is your own health and the other medicines you take, and that’s exactly what a consultation checks. Everyone buying Tadalafil or Sildenafil from The Family Chemist completes a short one so our team can confirm it’s safe for you.
Side effects
Because they work the same way, the two share the most common side effects: headache, facial flushing, indigestion, a blocked nose and dizziness. The differences are small:
- Tadalafil is more likely to cause back pain and muscle aches, which can linger a little longer because the drug stays in your system for longer.
- Sildenafil is more likely to cause temporary changes to vision, such as blurred sight or a blue tinge to what you see.
In rare cases, both can cause a prolonged, painful erection (priapism). If an erection lasts more than four hours, seek urgent medical help.
Which one should I use?
The choice depends on you and your individual circumstances.
Sildenafil may suit you if you are happy to plan sex around an hour ahead, use it only occasionally, and want the lower-cost option.
Tadalafil may suit you if you want a longer, more spontaneous window, have sex more than once or twice a week (where the daily dose works well), or would rather not time your dose around a meal.
Plenty of men try one, see how they get on and switch if it doesn’t work for their lifestyle. That’s normal, and a prescriber can guide it.
Complete a quick consultation with The Family Chemist, and our clinical team will help you find the option that’s safe and right for you.
Frequently Asked Questions
Is Tadalafil better than Viagra?
Viagra is a branded version of Sildenafil; neither is universally better. Tadalafil lasts much longer, while Sildenafil is a fast, occasional-use option that’s often cheaper.
How long do they take to work, and how long do they last?
Sildenafil usually works within 30–60 minutes and lasts about 4–6 hours. Tadalafil starts working from around 30 minutes after taking it and can last up to 36 hours.
Can I drink alcohol with Tadalafil or Sildenafil?
A small amount is unlikely to cause problems, but drinking more raises the risk of dizziness and low blood pressure, and heavy drinking can cause erection problems. The NHS advises limiting alcohol while taking either medicine.
Can I switch between Tadalafil or Sildenafil, or take both?
Never take two ED tablets at the same time. Switching from one to the other is common and safe when done on a prescriber’s advice.
Is there another option if I struggle with tablets?
Yes. Hezkue is an oral Sildenafil spray, a fast-acting alternative for anyone who doesn’t want to take tablets.
How we reviewed this article:
Sources
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Tadalafil 10mg film-coated tablets, emc [Accessed 2 July 2026]
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Sildenafil 50 mg film-coated tablets, emc [Accessed 2 July 2026]
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Tadalafil, NHS [Accessed 2 July 2026]
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Current version
-
6th Jul 2026 Medically reviewed by: Tannaz Sohrabi
-
1st Jul 2026 Edited by: Sunny Dhain, MPharmRS PGDip IndP
Sources
-
Tadalafil 10mg film-coated tablets, emc [Accessed 2 July 2026]
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Sildenafil 50 mg film-coated tablets, emc [Accessed 2 July 2026]
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Tadalafil, NHS [Accessed 2 July 2026]
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Sildenafil (Viagra), NHS [Accessed 2 July 2026]
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Direct comparison of tadalafil with sildenafil for the treatment of erectile dysfunction: a systematic review and meta-analysis, Springer [Accessed 2 July 2026]
-
Current version
-
6th Jul 2026 Medically reviewed by: Tannaz Sohrabi
-
1st Jul 2026 Edited by: Sunny Dhain, MPharmRS PGDip IndP
-
15th Jan 2026 Written by: Sunny Dhain, MPharmRS PGDip IndP
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Medically reviewed by:
Tannaz Sohrabi
Last reviewed: 6th Jul 2026
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