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Sildenafil dosage: how much sildenafil is too much?

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Reviewed by Chimene Richa, MD, written by Linnea Zielinski

Last updated: Oct 12, 2022
5 min read

Sildenafil (brand name Viagra; see Important Safety Information), is an effective treatment for erectile dysfunction. But sildenafil doesn’t give you an immediate erection. The medication requires sexual arousal to work properly. So if you’re expecting fireworks and left disappointed, it’s understandable that you may consider doubling or increasing your sildenafil dosage—but don’t do this.

Sildenafil, like all medications, comes with a risk of side effects and contraindications. If you’re wondering how much sildenafil is too much, make an appointment with a healthcare provider to discuss your concerns and potentially increase your dosage instead of taking matters into your own hands.


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Sildenafil side effects

With any medication, it’s common for healthcare providers to prescribe the minimum effective dose—the smallest dose that will work for you. That’s because the higher the dose of a medication, the higher the risk of side effects. Sildenafil is no exception.

Some sildenafil side effects include headache, redness in the face, changes in vision, stuffy nose, muscle aches, back pain, nausea, dizziness, and rash. The frequency of these side effects may increase dramatically with a higher dose. For example, 16% of people who take 25 mg of sildenafil experience headaches. At a higher dose of 100 mg, 28% of people experience headaches (DailyMed, 2017).

There have been numerous reports of people who have taken more than the recommended amount of Viagra. While we still don’t know all the risks associated with taking too much ED medication, one potential complication is an eye problem called retinal toxicity. This can cause blurred vision, changes in color vision, and light sensitivity. Fortunately, these symptoms usually go away after you stop taking the medication, but some people suffer permanent damage (DailyMed, 2017; Kim, 2017; Kolomeyer, 2018).

Ensuring that you can tolerate the medication is one reason healthcare providers typically start with a smaller dose and increase the dose according to your needs. Following your healthcare provider’s instructions minimizes your risk of adverse effects.

How much sildenafil is too much?

As with all medication, you should take the recommended dose of sildenafil prescribed to you by your healthcare provider, and no more. You also shouldn’t take sildenafil more than once every 24 hours. Your healthcare provider will likely start you on a 50 mg dose of the medication to test how well you respond to it. Your healthcare provider may increase your dose to 100 mg or decrease it to 25 mg, depending on whether you achieve the desired results and/or experience side effects.

You should take sildenafil at least 30 minutes before sex, but you can take it up to four hours in advance. Talk to your healthcare provider if your prescription isn’t helping you get and maintain erections firm enough for satisfying sex. Do not take an extra dose of sildenafil if the first one didn’t work. If you took sildenafil less than 30 minutes before sex, give it a little more time, as its effects may strengthen.

As you adjust your sildenafil dosage (with the guidance of a healthcare provider) for the best results, other options exist to help you get and maintain erections. Penis pumps and cock rings help draw blood into the penis for a firmer erection (with a penis pump) and prevent the blood from draining (with a cock ring). 

Sildenafil dosage

A 25 mg sildenafil dosage is considered a low dose, and low-dose sildenafil is only used in certain circumstances. If you’re over the age of 65 or if you’ve ever experienced side effects when taking the standard starting dose (50 mg), you may be prescribed low-dose sildenafil. Your healthcare provider also may prescribe low-dose sildenafil if you have kidney or liver medical conditions or are taking certain medications (DailyMed, 2017).

Researchers have used doses as high as 200 mg to treat severe erectile dysfunction, but more research is needed on the safety of high dosages. One small study of 54 participants with erectile dysfunction showed that high-dose sildenafil improved erectile dysfunction in just 13 of the 54 participants (24.1%). At the highest dose, 63% of the participants reported experiencing side effects like headaches and facial flushing, which was also true in patients who didn’t notice improvements in their erectile dysfunction symptoms (McMahon, 2002). 

Even among the participants who saw improvements in their erectile dysfunction symptoms, the side effects were so severe that many decided it wasn’t worth it. Of the 13 participants who had success with the high-dose treatment, 31% refused to continue because of the adverse effects. (McMahon, 2002).

Your healthcare provider will weigh the pros and cons of various sildenafil doses to help you make the right decision.

Sildenafil alternatives

If sildenafil doesn’t work for you, there are plenty of other safe and effective options to treat erectile dysfunction. Sildenafil is a member of a class of drugs known as PDE-5 inhibitors, which include alternative medications like tadalafil (Cialis; see Important Safety Information), vardenafil (Levitra), and avanafil (Strendra).

Depending on your lifestyle, one of these medications may work better for you than sildenafil: 

  • Tadalafil takes 1–2 hours to work, but its effects can last up to 36 hours off and on. Tadalafil is available in a daily tablet, while other PDE-5 inhibitors are taken just before having sex. 
  • Vardenafil may be the best option if you plan to take your medication with food. High-fat meals can slow down other PDE-5 inhibitors, but vardenafil works at the same speed even when taken with a moderate-fat meal (Zucchi, 2019). 
  • Avanafil works within 15 minutes for many people, making it the fastest-acting PDE-5 inhibitor currently available (DailyMed, 2021). 

As with any medication, a good rule of thumb is to take sildenafil as prescribed by your healthcare provider. The symptoms of erectile dysfunction are frustrating, but your healthcare provider is there to help you develop a treatment plan that’s right for you. 


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.


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Dr. Chimene Richa is a board-certified Ophthalmologist and Senior Medical Writer/Reviewer at Ro.