Tadalafil 20mg: Dosage, Effects, and How It Compares to Other Options

Tadalafil 20mg is the highest available dose of the active ingredient in Cialis, and for many men it's the most effective option for treating erectile dysfunction. But it's not automatically the right starting point, and it's certainly not the only option worth considering.

This article covers how tadalafil 20mg works, when it's appropriate, how it compares to other doses and treatments, and what to realistically expect from it.

How tadalafil works#

Tadalafil belongs to a class of drugs called PDE5 inhibitors (phosphodiesterase type 5 inhibitors). When you're sexually aroused, nitric oxide is released in the penis, triggering a chain of events that relax smooth muscle and increase blood flow. PDE5 is an enzyme that interrupts this process. Tadalafil blocks PDE5, letting the natural response continue and making it easier to get and maintain an erection.

Importantly, tadalafil doesn't cause an erection on its own. Sexual stimulation is still required. What it does is make your body's natural response more effective when arousal is present.

Tadalafil is also licensed in the UK for benign prostatic hyperplasia (BPH, or an enlarged prostate), which is why some men take a daily low dose even when ED isn't their primary concern.

Tadalafil 20mg specifically: what makes it different#

The main clinical advantage of the 20mg dose is efficacy. Clinical trial data consistently shows higher success rates at 20mg compared to 10mg. Roughly 76-85% of men taking tadalafil 20mg reported being able to have penetrative sex, compared to 68-77% at the 10mg dose.

The other defining feature of tadalafil across all doses is its duration. Effects can last up to 36 hours, which is significantly longer than sildenafil (Viagra), which typically works for 4-6 hours. This longer window is why tadalafil is sometimes called the 'weekend pill' and why many men prefer it for spontaneity.

The 20mg dose doesn't extend that window further compared to 10mg. Both doses provide the same approximate duration. The difference is the strength of effect within that window, not how long it lasts.

As-needed vs daily tadalafil: which approach suits you?#

This is often the more important decision than which specific dose to take.

As-needed tadalafil (10mg or 20mg) is taken roughly 30-60 minutes before sexual activity. You only take it when you want to. This suits men who have sex less frequently or who prefer not to take a daily medication.

Daily tadalafil (2.5mg or 5mg) is taken every day at a low dose, building a consistent level of the drug in your system so you don't have to plan around taking a tablet. This is particularly useful if you have sex two or more times a week, or if the need to take a pill before sex creates performance anxiety.

A systematic review and meta-analysis comparing the two approaches across six randomised controlled trials found broadly similar effectiveness for both methods overall. So the choice often comes down to lifestyle and preference rather than one being clearly superior.

At Totiva, both approaches are available. As-needed tadalafil starts from £7.49 for four 10mg tablets, while daily tadalafil starts from £9.99 for 28 tablets at 2.5mg. You can explore the options through Totiva's ED treatment page.

Tadalafil 20mg vs 10mg: when does the higher dose make sense?#

Most prescribers start with tadalafil 10mg. If you try it on at least four separate occasions without the results you hoped for, moving to 20mg is a reasonable next step.

The 20mg dose is more likely to be recommended if:

• You've tried 10mg and found it only partially effective
• You have underlying health conditions (such as diabetes or cardiovascular disease) that can make ED harder to treat
• A clinician has assessed your situation and considers the higher dose appropriate

You wouldn't typically start at 20mg unprompted. The dose escalation approach exists partly because side effects, while generally mild, are dose-dependent. Starting lower and adjusting makes clinical sense.

Tadalafil vs sildenafil: the key differences#

Sildenafil (the active ingredient in Viagra) is the other main ED treatment and the most commonly prescribed in the UK. Choosing between them is one of the most common questions men have.

Here's how they compare on the factors that tend to matter most:

Duration: Tadalafil lasts up to 36 hours. Sildenafil typically lasts 4-6 hours. This is probably the biggest practical difference.

Onset: Both take roughly 30-60 minutes to start working. Sildenafil may act slightly faster in some men, and tadalafil's full effect can take up to 2 hours.

Food interactions: Sildenafil is significantly affected by food, particularly fatty meals, which can delay absorption and reduce effectiveness. Tadalafil is much less affected by food, which gives it another practical advantage in terms of spontaneity.

Alcohol: Both medications interact with alcohol. Because both lower blood pressure, combining them with significant amounts of alcohol increases the risk of dizziness, flushing, and low blood pressure. Tadalafil's longer duration means you're technically 'covered' for longer, but drinking heavily during that window carries risks for both treatments.

Side effect profiles: Both share common side effects including headache, facial flushing, nasal congestion, and indigestion. Tadalafil has a slightly higher incidence of back pain and muscle aches, which is thought to be related to PDE11 inhibition.

Cost: Generic versions of both are available and substantially more affordable than the branded originals. Sildenafil is slightly cheaper per dose at baseline. At Totiva, sildenafil 50mg starts at £4.99 for four tablets, while as-needed tadalafil 10mg starts at £7.49 for four tablets.

A 2017 meta-analysis comparing tadalafil and sildenafil directly found both were effective, with patients generally rating their satisfaction similarly. Neither is universally 'better'. The right choice depends on your lifestyle, preferences, and how your body responds.

What are the side effects of tadalafil 20mg?#

Tadalafil is generally well-tolerated, but side effects are more common at the 20mg dose than at lower doses. The most frequently reported ones include:

• Headache
• Facial flushing
• Nasal congestion
• Indigestion or heartburn
• Dizziness
• Back pain or muscle aches (more specific to tadalafil than other PDE5 inhibitors)

These are usually mild and resolve within a few hours. Back pain and muscle aches, when they occur, typically appear 12-24 hours after taking the tablet and resolve within 48 hours.

More serious but less common side effects include a sudden drop in blood pressure, priapism (a prolonged, painful erection lasting more than four hours, which requires urgent medical attention), and sudden changes in vision or hearing. If any of these occur, seek medical help immediately.

Drug interactions to be aware of: Tadalafil should never be taken with nitrates (used for chest pain or heart conditions) as the combination can cause a dangerous drop in blood pressure. It also interacts with alpha-blockers and some antihypertensives, which are commonly prescribed in the UK. If you take medication for blood pressure, heart conditions, or prostate problems, this needs to be flagged during your consultation.

Grapefruit juice can affect how tadalafil is metabolised in the body, potentially increasing side effects, so it's worth avoiding while using it.

Can tadalafil work if other treatments haven't?#

If you've tried sildenafil and found it didn't work well, switching to tadalafil is worth exploring rather than concluding ED medication doesn't work for you. The two drugs have different pharmacological profiles and some men respond better to one than the other.

It's also worth reviewing how you took the medication. Sildenafil taken after a heavy meal, or tadalafil taken without allowing sufficient time before sex, may give misleading results. Timing, food, alcohol consumption, and anxiety all affect how well PDE5 inhibitors work.

If tadalafil 10mg hasn't been fully effective after four genuine attempts under good conditions, escalating to 20mg is a reasonable step. If 20mg also proves ineffective, a clinician should assess whether there are underlying causes contributing to the ED, such as low testosterone, vascular disease, or a medication side effect, that may need addressing separately.

Branded Cialis vs generic tadalafil: is there a difference?#

Cialis is simply the brand name for tadalafil. The active ingredient, mechanism, dosages, and effects are identical. The difference is purely cost.

Branded Cialis is considerably more expensive than generic tadalafil. In the UK, once the patent expired, multiple manufacturers began producing tadalafil, bringing costs down significantly. Cialis Together (tadalafil 10mg) is available over the counter without a prescription in the UK, while prescription tadalafil at 20mg requires a consultation.

At Totiva, generic as-needed tadalafil 20mg is available from £8.49 for four tablets. Branded Cialis Together 10mg is also available, starting from £14.99 for four tablets, if you prefer the branded option.

Getting tadalafil on the NHS vs private prescription#

Tadalafil is available on the NHS, but access can be inconsistent. NICE guidance supports its prescription for ED, particularly where there's an underlying cause such as diabetes or cardiovascular disease. However, GP appointments aren't always easy to get, and some men find discussing ED in a face-to-face appointment uncomfortable.

The NHS prescription charge in England is currently £9.90 per item. In Scotland and Wales, prescriptions are free, which affects the value calculation for private prescriptions in those regions.

Private online prescriptions through registered pharmacies like Totiva offer a straightforward alternative. The consultation is free, and you only pay for the treatment if it's approved. There's no need for an in-person appointment, and prescriptions are reviewed by UK-registered clinicians.

Lifestyle factors that support ED treatment#

Tadalafil works better in a body that's already in reasonable shape. That's not a criticism; it's simply that ED has multiple contributing factors and medication addresses one part of the picture.

Regular aerobic exercise has good evidence behind it for improving erectile function, partly by improving cardiovascular health and partly through testosterone and nitric oxide effects. Reducing alcohol consumption, maintaining a healthy weight, managing stress, and addressing sleep quality all contribute.

For men whose ED has a significant psychological component, whether that's performance anxiety, stress, or relationship factors, medication alone may not resolve things fully. Combining tadalafil with psychological support or couples therapy tends to produce better outcomes than either approach in isolation.

Starting treatment#

If you're considering tadalafil 20mg, or want to work out whether the 10mg dose, daily tadalafil, or sildenafil would suit you better, a consultation with a pharmacist or prescriber is the right starting point. There's no one-size-fits-all answer, and the best dose depends on your health history, other medications, and personal preferences.

Totiva's online consultations are free and reviewed by UK-registered clinicians. You complete a health questionnaire, a prescriber assesses your suitability, and if approved, your treatment is delivered discreetly. If you'd like to get started, you can begin a free ED consultation here.