Which Drug For Erectile Dysfunction? The Full List

Written by
The Manual Team
Medically approved by
Dr Earim Chaudry
Last updated
7th January 2022

In 30 seconds…

Since the licensing of Viagra back in 1998, erectile dysfunction (ED) drugs have been the most popular and effective method for improving erectile function in men. These days, however, Viagra is no longer the only drug for ED on the market.

Unbranded Sildenafil, the active ingredient in Viagra, is becoming as popular as the branded original. Meanwhile, Tadalafil, which powers the “weekend pill” Cialis, is increasingly known as an alternative. There are also less popular alternatives to combat ED, including Levitra and Spedra. All drugs are user-dependent in terms of their effectiveness, but these two differ in their potential side effects.

Others – such as Kamagra – are downright dangerous and should always be avoided.

Erectile dysfunction (ED) isn’t fun, we know. However, with 40% of men under 40 having experienced it to some degree, effective drugs have been developed to meet the large global demand for treatment. 

You’ll probably know at least one of these drugs. However, the market for ED drugs is no longer dominated just by Viagra. Rather, there are other tablets out there that can help you to get it up when you need it. But before popping any pills, it’s important to be fully-informed. If you think ED is no fun, try taking meds that don’t do the job – or unapproved substances that do you harm. 

In this article, we’ll be looking at the best medicinal treatments for erectile dysfunction. We’ll be mentioning one of the worst too – so you know exactly what to avoid.

Let’s take a look at the ED drugs you need to know…

Viagra and Unbranded Sildenafil

Of all drugs to treat ED, Viagra is the most famous. That’s mainly because it was the first. However, its success has also been down to exceptional marketing – and to the fact that it really does work.

The “little blue pill”, as it is known, was patented back in 1996 and was first licensed for ED use in 1998. Back then, it was the erectile dysfunction drug that the world needed, with sales of this “Vitamin V” in 2000 making up over 90% of the ED drug market. 

And it did deserve its success. According to one study, Viagra works in over 80% of guys. Meanwhile, another study found that it makes men with ED 500% more likely to have a fully rigid erection. 

Viagra contains the active ingredient, Sildenafil, a substance clinically known as a PDE5 inhibitor. It works on the principle that most erectile dysfunction cases are due to issues of blood flow to the penis, a process in which the enzyme PDE5 is involved. By inhibiting the effect of this enzyme, more blood can flow to where it is needed and, crucially, it can stay there too.

You can take Viagra once daily, though it is not recommended to take it more often than this. Ensure that it’s inside you an hour before sex – as this is when it will be most effective – and expect it to last for between 4 to 5 hours.

Generic Unbranded Sildenafil

Whilst Viagra dominated the early erectile dysfunction drug market, in 2013 its patent expired outside the US. This came with big pros for men suffering from ED, as it meant that Sildenafil – Viagra’s active ingredient – came to be available at a much cheaper price.

Sildenafil is the substance in Viagra that does the work. However, you can now buy the same thing as a generic drug. The effects of Viagra and Sildenafil are exactly the same: the same wait before it takes effect, the same length of effectiveness, and the same success rate too. 

The only difference is the price – because Sildenafil doesn’t come with the brand and image that Viagra boasts. You’re looking at less than half the price – for an effect that is identical.

Cialis (Tadalafil)

An alternative to Viagra that you might know is Cialis. It’s sometimes known as the “weekend pill”, because it works slightly differently to Sildenafil: its effects last a fair bit longer. 

This particular ED drug works on similar science to Viagra, however. It’s active ingredient, Tadalafil, is another PDE5 inhibitor, which, as you’ll now know, targets that particular enzyme responsible for smooth muscle contraction within the vessels supplying your penis. The overall rate of effectiveness is, like Viagra, just over 80%.

The slight difference between Cialis and Viagra, though, is that Cialis stays in your system for longer. Its effects can be felt for up to 36 hours (they don’t call it the “weekend pill” for nothing), compared to Viagra’s 4 to 5 hours. This means that you have a bit more spontaneity. 

Also, due to the particular chemical structure of Tadalafil, it is more easily tolerated than Viagra – meaning that side effects are less likely. 

That feature of Cialis – that it lasts longer – was seen as the ED drug’s main selling point by its manufacturers. And it also tends to take effect quicker – it’s advised to take Tadalafil 30 minutes before anticipated sexual intercourse. Like Viagra, the patent for Cialis has now expired. This means that there are generic unbranded Tadalafil options that do exactly the same work.

Like Sildenafil and Viagra, the difference is one of cost. Where you’ll pay about £9.50 for a tablet of Cialis, generic Tadalafil goes for £3 a pill

Cialis (Tadalafil)

The weekend pill

Known as the “weekend pill” because it is effective for up to 36 hours, Tadalafil is the generic, unbranded version of Cialis. Clinically proven to help you get an erection when you need it.

Best for
Weekend use
Effective in
Effective in 8 out of 10 men
2.5mg, 10mg, 20mg

Levitra (Vardenafil)

Levitra used to be the third horse in the race between the erectile dysfunction drug brands. However, its effect is very similar to that of Viagra – but without many advantages. 

Its active ingredient, Vardenafil, is another of the PDE5-inhibitors – which means it works in exactly the same way as Sildenafil and Tadalafil. In fact, like Viagra, it is effective usually for between 4 and 6 hours – and should be taken an hour before you need it. 

However, a survey of 150 trials found that Vardenafil is the ED treatment most commonly associated with side effects, which occur in about 25% of cases. Despite this, it is often suggested to men who do not respond effectively to Sildenafil or Tadalafil first.

Spedra (Avanafil)

The final erectile dysfunction drug we’ll look at here is Avanafil, which is available under the brand names Spedra or Stendra. Again, the active agent here is a PDE5-inhibitor. 

Avanafil has the advantage of being the least likely to cause side effects, according to the same study referenced previously. However, it is also shown to be the least effective, being only 20% more effective than a placebo. Unless you are in the small minority of men who do not respond to Tadalafil or Sildenafil, we don’t recommend that you go for this as a first option. 

That said, ED treatment is always user-dependent, so everyone will tolerate and respond differently.


You may have heard of another “ED treatment” that also contains Sildenafil. Some of you definitely have, because “Kamagra” is Googled roughly 100,000 times a month in the UK alone. 

However, don’t take your relationship with Kamagra – an unlicensed “ED drug” made in India – past Google. Being unlicensed, it cannot be legally sold as a medicine in the UK, and you cannot even be sure that the “drug” will even contain what or how much it claims to. The problem there is that a dodgy dose of Sildenafil could cause some serious trouble in the areas you are trying to help. 

When there are safe, legal, and effective erectile dysfunction drugs like Sildenafil and Tadalafil out there, dabbling in Kamagra is not worth the risk. Just don’t bother. Read more about Kamagra on our blog.

Key Takeaways…

Viagra and Cialis are the most famous erectile dysfunction drugs on the market, and rightfully so. Their active ingredients are shown to be highly effective for men experiencing ED. Fortunately, these drugs are not under patent protection anymore, so you can access Sildenafil and Tadalafil – the same active ingredients – more affordably whilst achieving the same desired result. 

If you have any questions about which drug is most suitable to your own individual situation, contact one of Manual’s clinicians today.

Erections aren’t always easy for millions of men in the UK. It’s no big deal. Choose from highly effective, clinically proven solutions.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Further reading

From our health centre. Experts, information and hot topics. See all Erectile Dysfunction articles

Ed by Manual

Erectile dysfunction treatments

Erections aren’t always easy for millions of men in the UK. It’s no big deal. Choose from highly effective, clinically proven solutions.