When should you take an ED tablet?

Erectile dysfunction (ED) is when you can’t get or keep an erection (1). ED isn’t something to be ashamed of. It’s very common, especially in males over 40 years old (1). ED tablets can help (1). You can request an ED tablet prescription through our website.

What are the different types of ED tablets?

The main ED treatments are tablets including:

• Tadalafil (Cialis) (1)
• Sildenafil (Viagra) (1)
• Vardenafil (Levitra) (1)
• Avanafil (Spedra) (1)

ED tablets are widely used (2).

Do you need a prescription for ED tablets?

You’ll usually need a prescription for ED tablets. A pharmacist will be able to help work out if treatment is right for you and which one will likely work best.

Remember, there is nothing to be ashamed of. Pharmacists are not there to judge - they want to help you.

How do ED tablets work?

ED tablets help cause an increase in blood flow to the penis (2) but they don’t:

• Work instantly (2)
  • 2.5mg or 5mg tadalafil (Cialis) tablets that are taken daily can take up to 2 weeks to start working (3)
  • 10mg or 20mg tadalafil (Cialis) tablets that are taken each time you plan to have sex should be taken at least 30 minutes before sexual activity (3)
  • Sildenafil (Viagra) tablets should be taken at least 30 minutes before sexual activity (though they can sometimes take up to an hour to work) (4)
• Create erections automatically
  • After waiting for the medicine to work, you will need to stimulate yourself sexually and be sexually excited (aroused) to get an erection. (3) The medicine won’t work if you don’t do this. (3)

How do you use tadalafil (Cialis)?

Tadalafil can be taken with or without food (3).

There are two different forms:

1. 2.5mg and 5mg tablets
   • 1 tablet should be taken every day whether you have sex or not
     • This is so the medicine is always in your body so it’s continuously working
     • This means whenever you’re aroused and sexually stimulated, you can get an erection
   • These tablets are recommended if you experience ED regularly and enjoy sex 2 to 3 times per week
   • If you take tadalafil every day for the first time, it can take up to 2 weeks to start working
2. 10mg and 20mg tablets
   • 1 tablet should be taken at least 30 minutes before sex
     • After waiting for the medicine to work, you’ll need to stimulate yourself sexually and be aroused to get an erection
     • The medicine won’t work if you don’t do this
   • These tablets are recommended if you:
     • Only experience ED sometimes
     • Don’t want to take a tablet every day

How do you use sildenafil (Viagra)?

You should take a tablet at least 30 minutes before sex (4). Sometimes it can take up to an hour to work (4). It’s best to take it without food and when you haven’t eaten in a while (on an empty stomach). Food can cause a delay in the tablets working.

After waiting for the medicine to work, you’ll need to stimulate yourself sexually and be aroused to get an erection (4). The medicine won’t work if you don’t do this (4).

If you haven’t used sildenafil before, it’s best to start with a 50mg dose (4). If you struggle to get an erection or it doesn’t last long enough, we will likely recommend increasing to a 100mg dose (4). In this case, you can take two 50mg tablets or one 100mg tablet (4).

You can’t take more than 100mg at one time, and you can only take this medicine once every 24 hours (4).

How long do tadalafil (Cialis) and sildenafil (Viagra) last?

Tadalafil (Cialis) can last up to 36 hours (3). Sildenafil (Viagra) lasts for about 4 hours (4). This means, during this time, if you sexually stimulate yourself and are aroused, the treatment will help you get an erection (3).

What are the side effects of tadalafil (Cialis)?

Some common side effects of tadalafil (Cialis) include (5):

• Headaches (5)
• Red skin on the face, neck, or upper chest (flushing) (5)
• Pain, discomfort, or bloating in the tummy (gastrointestinal discomfort) (5)
• Stuffy or blocked nose (nasal congestion) (5)
• Muscle aches and pains (myalgia) (5)

You can speak to a pharmacist or doctor about the side effects of treatment. Always report any side effects you experience to a healthcare professional.

What are the side effects of sildenafil (Viagra)?

Some common side effects of sildenafil (Viagra) include:

• Headaches (6)
• Cough (6)
• Hair loss (alopecia) (6)
• Anxiety (6)
• Feeling dizzy or like you’re going to be sick (nausea) (6)
• Night sweats or trouble sleeping (insomnia) (6)
• Stuffy or blocked nose (nasal congestion) (6)
• More often, loose, or runny poos (diarrhoea) (6)
• Increased risk of infection (6)
• Skin reactions or swelling (fluid retention) (6)
• Uncontrollable shaking in one or more parts of your body (tremor) (6)
• Low blood pressure (vasodilation) or lack of healthy red blood cells (anaemia) (6)
• Problems with eyes and sight (vision disorders) (6)

You can speak to a pharmacist or doctor about the side effects of treatment. Always report any side effects you experience to a healthcare professional.

What should I do if ED tablets don’t work?

Even if you have taken the medicine correctly, are aroused, and have stimulated yourself, you may not always get an erection. You should speak to a pharmacist if your treatment isn’t working.

Your pharmacist may advise you to try taking:

• The same tablets a few more times, so your body can get used to them
• A tablet at a different time of the day
• A new prescription for the tablets with a different amount of medicine in them (different strength, usually in mg)
• A new prescription for a different tablet

Many people need to try some of these strategies before finding what works best.

Where can I buy ED tablets?

You usually need a prescription from a pharmacist or doctor to get ED tablets such as sildenafil and tadalafil.

You can request prescription treatment directly through our service, all supplies are subject to medical review by an independent doctor:

1. Select your medical condition or a suggested treatment
2. Complete the online consultation

We are a team of UK-based doctors and pharmacists who can help you access safe, regulated treatment. We know that seeking treatment for any condition can be daunting. This is why we’re always discreet, professional, and understanding. We can give you advice and answer any questions you may have.

Where can I find out more?

1. Erectile Dysfunction [Internet]. NHS. 2023 Jul 28.
2. Erectile Dysfunction Treatment [Internet]. Oxford Online Pharmacy. 2024 Feb 28.
3. Tadalafil Tablets [Internet]. Oxford Online Pharmacy. 2024 Nov 07.
4. Sildenafil Tablets [Internet]. Oxford Online Pharmacy. 2024 Mar 27.
5. Tadalafil [Internet]. NICE (National Institute for Health and Care Excellence) BNF (British National Formulary). 2025.
6. Sildenafil [Internet]. NICE (National Institute for Health and Care Excellence) BNF (British National Formulary). 2025.