To ensure you’re getting the best results from sildenafil, you should make sure that you’re using it correctly and safely.
Below we have detailed the answers to some of the most commonly asked questions about taking sildenafil correctly. If you want to find out about the possible side effects of sildenafil, you can find a separate article about that here.
What is sildenafil?
Sildenafil is a medication used to treat erectile dysfunction which is effective and generally well-tolerated. But like any other medication, it needs to be taken exactly as your doctor or pharmacist has instructed.
How does it work?
Sildenafil works by allowing your arteries to relax and open, by making more of a chemical called cGMP available. Increasing blood flow through the arteries in the penis means improved erectile function.
Cells in your arteries normally release nitric oxide, which, via molecular messengers including cGMP, sends instructions to muscle proteins to relax. This causes increased blood flow into your penis, which causes an erection. An enzyme called PDE-5 normally breaks down that cGMP, which reverses that relaxation, allowing your erection to subside. Sildenafil, a PDE-5 inhibitor, helps maintain that erection instead.
Can anyone take sildenafil?
There are some situations where you should not take sildenafil.
Check with your doctor first if …
- You’re taking medications known as nitrates
- You’re taking alkyl nitrites (also known as “poppers”)
- You’re taking medications known as protease inhibitors
- You’re taking medications known as alpha-blockers
- You’re already taking sildenafil or any other PDE5 inhibitor in another form
- You have any heart, liver or kidney problems
- You have low blood pressure
- You have any eye disease
- You have any blood disease
- You have a penile deformity
- You have a stomach ulcer
- You are taking medications for pulmonary arterial hypertension
- You’re lactose-intolerant
- You’re under the age of 18
- You’re a woman
The recommended dose
The recommended starting dose is 50 mg. You shouldn’t take this more than once within a 24 hour period. Taking it more than once a day will increase the chance of side effects. If, after taking sildenafil, you feel the effect is too strong or too weak, you should talk to your doctor or pharmacist who may suggest an adjusted dosage for you or an alternative treatment. You should not take sildenafil film-coated tablets in combination with sildenafil oro-dispersible tablets.
How to take sildenafil
Take your sildenafil about an hour before you plan to have sex. Swallow the tablet whole with a glass of water.
You can take it with or without food, but you might find that the effect takes longer to start if you’ve eaten heavily.
Alcohol can interfere with your ability to get an erection (we’ve written about it in detail here), so to maximise the benefit of sildenafil, it’s best to give the beer a miss. Grapefruit juice may increase the incidence of unwanted side effects of sildenafil.
The effects of sildenafil last approximately four hours, which means your erectile function is improved for four hours. The effects of sildenafil become evident when you are sexually stimulated or aroused.
You should not have an erection for four hours - a prolonged and painful erection (priapism) is a surgical emergency, and you should seek urgent medical attention should this happen.
What to expect
- Most people feel the effect of sildenafil in 45 minutes or so.
- You’ll need to have sexual stimulation or feel sexually aroused to get an erection.
- If nothing happens, or if not enough happens, you should inform your doctor.
- You may experience side effects, and some are more common than others
- Sildenafil may cause side effects which include dizziness and altered vision. You should be aware of your personal reaction to sildenafil before you drive or operate heavy machinery whilst taking it.
You should stop taking sildenafil if…
- you experience any sudden decrease or loss of vision;
- you experience any allergic reaction, such as wheeze, breathing difficulties, or swelling around the eyes or airways;
- you experience severe dizziness;
- you experience chest pains. (If you are on nitrate medications for chest pain, do not take them.)
Severe side effects are rare, but they do happen. If you do experience any of the above severe side effects, you should seek urgent medical attention.