Ghofrani, Hossein A et al. “Sildenafil: From Angina to Erectile Dysfunction to Pulmonary Hypertension and Beyond.” Nature Reviews. Drug Discovery vol. 5,8 (2006): 689-702. doi:10.1038/nrd2030.
One of the most effective medications for erectile dysfunction is sildenafil, which you probably know better as its brand name Viagra. It’s been helping men get and maintain erections for decades. Most people tolerate it well, but like with all medicines, sildenafil can cause side effects.
Here’s what you need to know and how best to manage them if symptoms do pop up.
What are the side effects of sildenafil?
Did you know that sildenafil was originally developed as a treatment for heart conditions like high blood pressure and chest pain?
It can help you get and maintain an erection by relaxing your blood vessels and increasing blood flow to your penis. But because it works on blood vessels elsewhere in the body, it can sometimes cause side effects. These are usually mild and manageable. And not all men get them.
The most common side effects of sildenafil are:
- headache
- dizziness
- blocked or stuffy nose
- stomach ache, diarrhoea or feeling sick (nausea)
Serious side effects of sildenafil
Sildenafil doesn’t usually cause serious side effects, especially if it’s prescribed by a clinician who has gone through your medical history. But in rare cases, they can happen.
Possible serious side effects of sildenafil include:
- an allergic reaction (anaphylaxis) which causes symptoms like a swollen throat or tongue, a raised itchy rash and breathing problems
- blistering skin around your mouth, eyes, nose or genitals
- heart attack, which causes chest pain that feels tight or like squeezing on your chest, feeling short of breath and sweating
- a fast or irregular heartbeat
- seizures (fits)
- fainting
- painful erections that last longer than 4 hours (called “priapism”)
Don't wait for these symptoms to pass; call 999 or 111 for urgent medical help.
How long do sildenafil side effects last?
Even if you do experience sildenafil side effects, chances are, they won’t last very long. Most sildenafil side effects fade within 3 to 5 hours. Symptoms such as headaches, facial flushing and indigestion usually peak after an hour.
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Do sildenafil side effects vary by dose?
Yes. As a general rule, the higher the dose, the more likely you are to notice side effects. And when it comes to ED meds, taking a higher dose doesn’t necessarily mean you’ll get a better experience. Always take the dose you’ve been prescribed.
Sildenafil usually comes in three doses: 25mg, 50mg and 100mg. Most men will start on 50mg.
The side effects themselves are broadly the same at each dose, but they can become more noticeable as the dose increases.
Your clinician will recommend the most appropriate dose for you.
How to reduce sildenafil side effects
You can’t always avoid medication side effects, but a few simple changes can make them less likely or easier to manage.
Take sildenafil as prescribed
Follow your clinician’s advice and give sildenafil time to work. It usually takes around 30-60 minutes to kick in, and you need to be sexually stimulated. Don’t take another tablet because you haven’t got an instant erection. Taking more sildenafil will increase your risk of side effects.
Watch what you eat
If you take sildenafil with a large or high-fat meal, it can take longer to kick in.
Go easy on alcohol
Alcohol can make dizziness or lightheadedness more likely, and can make it harder to get an erection in the first place.
If you do get mild side effects, don’t panic
If you do get a headache, flushing or dizziness, these usually settle on their own as the medicine wears off. Staying hydrated and avoiding alcohol can help.
Speak to your clinician
If your side effects are severe, persistent or happen every time you take sildenafil, speak to your prescriber about whether a lower dose or different ED treatment could work better for you.
Long-term side effects of sildenafil
The good news is that sildenafil doesn’t usually cause any lasting side effects, as the drug leaves your body within a few hours.
That said, if you’re regularly relying on sildenafil or your ED is getting worse, speak to your GP. Erection problems can sometimes be an early sign of other conditions, so it’s always worth getting it checked out.
Can sildenafil affect blood pressure?
Because sildenafil works by relaxing your blood vessels, it can cause a temporary drop in blood pressure. This isn’t a problem for most healthy men, but it can sometimes make you feel dizzy or lightheaded after taking sildenafil.
You must never take sildenafil with nitrates (often prescribed for angina or taken recreationally as “poppers”). This combination can cause a dangerous drop in blood pressure.
Tell your clinician about any medications you’re taking before you start treatment for ED.
Sildenafil vs tadalafil: which causes fewer side effects?
Sildenafil and tadalafil (which is available as a daily pill) both work in a similar way, so their side effects are broadly similar. But tadalafil can also cause symptoms such as back pain and coughing.
Neither is automatically the safer option; it comes down to how your body responds and what works best for you.
Who should not take sildenafil?
Sildenafil is safe for many men, but it's not right for everyone.
You shouldn't take it if you:
- take nitrate medicines for angina or chest pain
- have been advised to avoid sex because of a serious heart condition
- have very low blood pressure
- have previously had a serious allergic reaction to sildenafil
- have certain rare inherited eye conditions
You should also tell your clinician if you have heart or blood pressure problems, liver or kidney disease, or take medicines for high blood pressure or an enlarged prostate.
Get your confidence up
Sildenafil is one of the most effective treatments for erectile dysfunction, but it's not your only option. And you shouldn't have to put up with side effects to get your sex life back on track.
Whether it’s getting hard, staying hard or lasting longer, we’ll find the right plan for you. Take our quick quiz to get started.
Low testosterone can also contribute to ED, particularly if you're experiencing a reduced sex drive, fatigue or loss of strength. Getting your T levels checked with an at-home testosterone blood test is the first step.
