Which ED Tablet, and What to Do When It Doesn't Work

Erectile dysfunction (ED) is a common condition that affects many men and there are a few types of erectile dysfunction treatments available in the UK. They all belong to the same drug class, so usually the choice of which treatment comes down to personal preference and what has worked before.

Each drug works in the same way, they all work by blocking an enzyme called PDE5, which normally breaks down the signal that tells the blood vessels in the penis to relax. By blocking the enzyme the signal lasts longer, so more blood flows into the penis and stays there. Contrary to popular belief none of them can cause an erection to happen on it's own, they need sexual stimulation to work.^[1][2] What will make the difference is how you want them to fit into your routine and what has previously worked for you.

Most treatments are "on demand" where the drug is taken around 30-60 minutes before sex, it is usually the cheapest option as you are only taking them when needed rather than daily. This includes drugs such as sildenafil and tadalafil 10mg and 20mg tablets.^[1][2] Though tadalafil is a bit different from the others as a single dose can last up to 36 hours, which is where its nickname as the "weekend pill" comes from, so its timing isn't as strict as sildenafil's. 

Daily medicines are lower doses taken daily, this means no planning is needed but you do need to take them every day. This includes tadalafil 2.5mg and 5mg tablets.^[2] If you are using "on demand" medicines more than twice a week a daily tablet may be worth looking into as it may fit into your routine better as well as save you some money.

If you're not sure on which to choose first, on demand first is the usual first order, just to see how you react to the medication.

Most of the headline figures for if these medications worked come from a single question asked once at the end of the trial: did treatment improve your erections, yes or no.

Across 21 randomised trials of sildenafil, between 65% and 82% of men reported improved erections, against 18% to 26% on placebo, with the figure rising steadily across the 25mg to 100mg dose range. ^[5] For tadalafil, 81% reported improved erections against 35% on placebo, and 75% of attempts at sex were successful against 32%. ^[2] The placebo figures are not small, and they vary enormously between trials. That tells you how much of erectile function is psychological even in men whose problem is physical, and it's the reason a single good night proves less than it feels like it does.

How bad the problem is to start with matters more than which drug you take. In the tadalafil trials, 86% of men with mild erectile dysfunction reported improvement, 83% with moderate, and 72% with severe. The placebo arms tell the same story more starkly: 45%, 42% and 19%. ^[2] If your problem is severe, expect a smaller effect and judge it against the right benchmark rather than against a headline aimed at everyone.

And the response climbs with dose, so sildenafil 50mg not working doesn't mean 100mg won't. It's worth discussing with your prescriber before you conclude the drug isn't for you.

Most men who say this medication doesn't work for them haven't given the medication a fair chance to work.

There is a study of 100 men who were classed as sildenafil non-responders. In 56 of them the drug was being used incorrectly and forty-five had never tried the highest recommended dose. Thirty-two had taken the tablet on a full stomach straight after a meal. Twenty-two had taken it immediately before sex rather than giving it time to work. Twelve didn't know that sexual stimulation was necessary at all. Only 34 of the hundred had ever been offered a follow-up appointment. After correcting the dose and the timing, 31 men responded to the same drug that had supposedly failed them. ^[6]

A separate group of men referred to a urologist as treatment failures were salvaged at a similar rate, around 41%, through re-education alone. ^[7] The same pattern was later shown for tadalafil and vardenafil, so it isn't a quirk of one drug. ^[8]

The dose was never increased. When we look at the evidence the simple fact is, the dose was never increased. This was the single most common problem, and it's the easiest to fix if it is safe to do so. Of the men who responded after correction in that study, two thirds needed the top dose to do it. ^[6]

It was taken after a meal. Food slows sildenafil down and blunts it, delaying the peak by an hour and cutting it by 29%. ^[1] A man who takes sildenafil after a three-course dinner hasn't tested sildenafil, he's tested a late, flattened version of it. This matters less for vardenafil, which is only really affected by genuinely fatty food, ^[3] and not at all for tadalafil. ^[2]

It was taken too late. Swallowing a tablet as things are getting started doesn't give it time to be absorbed. Sildenafil peaks between 30 minutes and two hours after the dose. ^[1]

There was no real arousal. These drugs amplify a signal that has to be there first. A surprising number of men take the tablet expecting it to do the work on its own.

It was tried once or twice. The chance of a successful attempt keeps climbing with each try and doesn't level off until around the eighth. ^[9] One tablet, on one occasion, on a night that mattered, doesn't give you enough information to make a decision whether the drug worked or not.

Performance anxiety can play a role here, and a bad experience makes the next attempt more loaded, which makes another bad outcome more likely. The tablet can break that cycle, but only if it gets enough goes on to produce a success that resets your expectations. In one re-education programme, 55% of men who had previously failed on sildenafil went on to succeed once they were taught to titrate to the maximum dose and given a minimum trial of eight attempts. ^[9]

So if you are one of the men finding that this medication does not work for you, make sure you are taking it on an empty stomach if it's sildenafil, give it an hour, and give it around eight separate attempts before concluding anything. If it still isn't working after that, go back to your prescriber rather than giving up, they may then suggest a dose increase, an alternative or review how you are taking it.

There's usually more than one thing going on that's causing your erectile dysfunction.

Blood flow. This is the most common cause, the arteries supplying the penis are around 1 to 2mm across, while the coronary arteries are 3 to 4mm. Narrowing affects all of them at the same rate, but it shows up in the smaller vessels first because there's less room to spare. ^[10] Ehy erections that fade gradually over months or years could be an early sign that your blood vessels need attention, typically appearing two to three years before any chest symptoms would. ^[11]{{citation(12}}

The useful part of that is the head start. International consensus updated in 2024 recommends that erectile dysfunction be treated as a reason to look more closely at cardiovascular risk, and the same panel found this applies even when the cause looks psychological rather than physical. ^[13] It might be worth booking in with your GP and undergoing a few routine checks: blood pressure, cholesterol, HbA1c or fasting glucose, and a risk score before taking any medication for erectile dysfunction, or if you have been taking medication for it but never spoke to your GP since, booking in with them for an "MOT".

Other medicines you are taking. A number of common prescriptions can cause or worsen erectile dysfunction. Beta-blockers are the blood pressure class most consistently linked to it, particularly the older ones, though nebivolol appears to be an exception and may improve erectile function. ^[14] ACE inhibitors, angiotensin receptor blockers and calcium channel blockers are generally neutral or slightly positive, so there's often somewhere else to go. ^[14] Thiazide diuretics were long blamed for this, but more recent evidence doesn't support it. {{citation(14}} Antidepressants, particularly SSRIs, are another common culprit, though it's worth separating the drug from the condition, since depression itself affects sexual function whether or not it's being treated. ^[15] Opioid painkillers have a marked effect through their impact on hormone levels, and this shows up in younger men more than people expect. ^[16] Finasteride, taken for hair loss or prostate symptoms, is also associated with it.

Diabetes. Erectile dysfunction is a recognised early sign, and for some men it's how their diabetes gets picked up. It's one of the reasons the blood test above is worth doing even if you feel well otherwise.

Testosterone. Low testosterone can contribute and it's worth testing, especially if you are over 30 and particularly if your sex drive has also dropped rather than just your erections. Treating your low testosterone could also treat your erectile dysfunction if it is caused by low testosterone.

Stress, anxiety and relationships. These are real causes and hard to solve quickly. Fast onset, problems only in certain situations, and normal morning erections all point this way. It is important to rule out the above problems first or get them checked out anyway, since the 2024 consensus found the cardiovascular link holds even where the cause appears psychological. ^[13]

The panel confirmed these tablets are safe in men with existing or suspected heart disease, and there's growing evidence they may be protective. ^[13]

When men taking sildenafil were given a full assessment alongside it, covering their medical history, an examination, proper information about the condition, help with risk factors and lifestyle, and counselling, 74% of 111 men went on to have successful sex. [9] Which is a noticeable improvement on taking the tablet alone.

Exercise, and weight. In a two year randomised trial of 110 obese men in their late thirties to mid fifties, those given intensive diet and activity support raised their physical activity from around 50 minutes a week to nearly 200. Roughly a third recovered normal erectile function, against 5% of the control group. [17] Note it did take them two years so do not expect a quick fix. And increased physical activity predicted improvement independently of how much weight was lost, meaning the exercise is doing something in its own right rather than just being a route to a smaller waist.

That trial was in obese men who didn't have diabetes, high blood pressure or high cholesterol, so it doesn't tell you what would happen for everyone, but it does give you a good indication.

Alcohol. A couple of drinks is unlikely to matter. Heavy drinking works directly against what the tablet is doing, and it's one of the most common reasons a man concludes his treatment has failed when it hasn't.

Smoking. Damages exactly the blood vessels these drugs depend on. Stopping is one of the few things here that helps on a timescale of months rather than years.

You don't need to sort your weight out before you're allowed treatment, take the tablet, and then work on the rest as you take it.

Before you fully write the tablets off, it's worth being sure the tablets have actually been given a fair go, for eight doses at the highest dose you can tolerate. If you've been to the maximum tolerated dose, taken it correctly, given it a proper run of attempts and had a look at what else might be contributing, and it still isn't working, then maybe consider other alternatives.

It would definitely be worth getting your testosterone levels get tested at this point. Guidance is that every man who doesn't respond to these tablets should have his testosterone measured. {{citation(19)}} What the evidence supports is narrower than the internet suggests. In a trial of 173 non-responders with low or borderline testosterone, adding testosterone gel to daily tadalafil only produced a meaningful benefit in the men whose levels were genuinely low rather than borderline. {{citation(18)}} Broader reviews have found inconsistent results. {{citation(19)}} So it's worth testing, and it's worth treating if you're properly deficient, but it isn't a general fix and it won't do anything if your levels are normal.

Alprostadil works through a different mechanism entirely, so it doesn't depend on the same pathway the tablets do. It's given either as a small injection into the side of the penis or as a pellet inserted into the urethra. Men tend to recoil at the description and then find it more manageable than they expected.

Vacuum devices draw blood into the penis mechanically and hold it there with a constriction ring. They suit some men well and they're a reasonable option where drugs are unsuitable, including men who can't take PDE5 inhibitors at all.

Beyond that there are surgical options. If you've genuinely tried the tablets, and found they've had no effect, you may want to book in with your GP who can then discuss your options and refer you onto a specialist.