• What is sildenafil and how does it work?

  Sildenafil helps treat erection difficulties by increasing blood flow to the penis during sexual stimulation. It works by relaxing blood vessels, making it easier to get and maintain an erection when you are aroused. This effect is strongest when ED is caused by reduced blood flow, and most men respond well when the dose and timing are correct.

• How long before sex should I take sildenafil, and how long does it last?

  Sildenafil is usually taken 30–60 minutes before sex, and you still need to be sexually aroused for it to work. For most men, its effects last around four to five hours, although this varies depending on dose, meals, alcohol intake, and overall health. Planning ahead helps ensure you take it at the right time for the best effect. 

• How effective is sildenafil for erectile dysfunction?

  Sildenafil works for about seven in ten men, especially when ED is linked to reduced blood flow rather than psychological causes. Using the right dose, taking it on time, and avoiding heavy meals can all improve results. If it isn’t effective, a prescriber may adjust the dose or suggest another ED treatment that better matches your symptoms and health.

• What are the common side effects of Sildenafil?

  The most common side effects include headache, flushing, indigestion, and a blocked nose, which are usually mild and short-lived. Some men notice dizziness or temporary changes in vision. Rarely, serious effects like chest pain or a prolonged erection lasting more than four hours can occur and need urgent medical attention. A prescriber will help check sildenafil is safe for you.

• Who should not take sildenafil?

  Sildenafil is not suitable if you take nitrate medicines, have very low blood pressure, severe heart or liver problems, or have recently had a heart attack or stroke. It’s also unsuitable for men with certain eye conditions. A prescriber will assess your medical history,  medicines, and symptoms to confirm whether sildenafil is safe and appropriate for you.

• Do I need a prescription for sildenafil in the UK?

  Most strengths of sildenafil require a prescription, but sildenafil 50 mg (Viagra Connect) can be supplied by a pharmacist after a short consultation. Higher or lower doses need a clinician to review your health and symptoms. This helps ensure you get the safest and most effective option for your type of erection difficulty.

• What’s the difference between sildenafil and Viagra?

  Viagra is simply the original brand name for sildenafil, and both contain the same active ingredient at the same strengths. They work in the same way and have similar side effects. Many men choose generic sildenafil because it offers the same clinical effect at a lower price while being held to identical safety and quality standards.

• Does sildenafil work better on an empty stomach?

  Sildenafil works reliably for many men, but a heavy or high-fat meal can delay how quickly it starts working. Taking it on an empty stomach or after a lighter meal usually helps it act faster and feel more effective. This is one of the most common reasons men think sildenafil “isn’t working” when the dose is actually correct.

• What dose of sildenafil should I start with?

  Many men start with the 50 mg dose, as it provides a good balance of effectiveness and tolerability. Some men may need 25 mg if they have side-effect concerns, while others may require 100 mg for a stronger effect. A prescriber will help choose the safest dose based on your symptoms, health conditions, and medication history.

• Why does sildenafil sometimes stop working?

  Sildenafil can feel less effective if taken incorrectly, after a heavy meal, or during periods of stress, tiredness, or anxiety. Health changes such as diabetes, blood pressure issues, or new medicines can also affect its performance. A prescriber can review your dose, timing, and symptoms to help improve results or suggest another ED treatment.

• Can sildenafil affect vision?

  Some men notice temporary visual changes such as a blue tint, blurred vision, or increased sensitivity to light. These effects usually settle as the medicine wears off. Very rarely, serious eye problems have been reported. If you have eye conditions or experience sudden vision changes, you should seek medical advice urgently.

• How long does sildenafil stay in your system?

  Sildenafil starts to wear off after about four to five hours, but small amounts can remain in the body for up to 24 hours. This doesn’t mean you’ll continue to have effects the whole time. Understanding how long it stays in your system helps guide safe dosing and avoid taking another tablet too soon.

• Does sildenafil work the first time you take it?

  Some men respond well on the first dose, but others may need to try sildenafil several times before seeing consistent results. Taking it correctly, avoiding heavy meals, and ensuring you feel relaxed and aroused all help it work more reliably. If it doesn’t work after a few attempts, a prescriber may review your dose or consider alternatives.

• Can sildenafil be used long term?

  Yes. Sildenafil is considered safe for long-term use when monitored by a clinician, and many men use it regularly for years without problems. Regular reviews help ensure the dose remains right for you and check for any new health issues or medication interactions that may affect safety or effectiveness.

If you have any questions, concerns, or need advice, our team is always available to help, just as you'd expect from your local pharmacy.