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How to Take Sildenafil for Erectile Dysfunction

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 11/22/2022

Okay, so your healthcare provider wrote you a prescription for sildenafil — now what? We’re glad you asked. Before you’re off to the races, there are a few things about sildenafil that you should know.

In this piece, we’ll be covering how to take sildenafil (generic for brand name Viagra) for ED, what you should know before taking it, side effects of sildenafil, and more.

How to Use Sildenafil

When you filled your prescription, the pharmacist probably gave you a quick rundown of the basics, which probably included a fair amount of confusing medical jargon. We’re here to break it down for you, so you know exactly how to take sildenafil for erectile dysfunction.

To start, there are typically three dose strengths of sildenafil that healthcare providers will prescribe, based on your needs — 25mg, 50mg and 100mg. For most patients, the recommended dose of sildenafil is 50mg taken as needed, approximately one hour before sexual stimulation.

Based on the effectiveness and ability to tolerate the drug, your healthcare professional may adjust the dosage up to 100mg or down to 25mg.

It is important to note here that the maximum dose per day is 100mg of sildenafil, so don’t take another 100mg if the first isn’t working the way it should. 

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How to Take Sildenafil With Food

Before popping that little blue pill, there are a few things you should know.

Sildenafil does not protect you from STIs. Therefore, you should always practice safe sex and wear a condom.

You can take sildenafil with food or on an empty stomach. However, a high-fat meal can block the absorption of sildenafil citrate and can make the drug less effective for your erection. 

If you do plan to eat a meal before taking sildenafil, make sure to have it as your breakfast or lunch. That way, it gives your body time to digest the food, making it quick and easier for sildenafil to absorb into the bloodstream.

Grapefruit juice may also impede or delay the absorption of sildenafil in the body. Make sure to seek medical advice from a healthcare provider about eating grapefruit and drinking grapefruit juice while taking sildenafil.

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What To Do if You Forget a Dose of Sildenafil

Since sildenafil is taken on an as-needed basis, there’s no need to worry about forgetting a daily dose. Simply take the drug approximately one hour before sex and you’ll be good to go.

This does mean, however, that you’ll need to be prepared ahead of time. Sildenafil does not allow for a high degree of sexual spontaneity, so if you expect to have sex within the hour, make sure to take your sildenafil ahead of time for ideal erection timing.

Don’t take it too early (more than three to four hours ahead of time), as the effects can wear off and you can lose your erection.

Side Effects of Sildenafil

As with any drug, sildenafil does come with its share of side effects. 

Common side effects include headaches, flushing, upset stomach, blurred vision, nasal congestion, muscle and back pain, nausea, dizziness and rash. Most of these common side effects are mild to moderate and will go away as your body adjusts to the drug.

Serious side effects of sildenafil also exist. These side effects include chest pain and sudden loss of vision, hearing loss and in some cases, allergic reaction. If you experience any of these serious side effects, seek medical attention right away.

An erection lasting longer than four hours (priapism) is also a serious side effect and is considered a medical emergency. If this happens to you, go to the emergency room right away to prevent permanent blood vessel damage in the penis.

If any of these side effects are affecting your quality of life, it’s worth it to talk to your healthcare provider about possible alternatives to sildenafil. Your healthcare provider can adjust your dose or recommend another ED drug for you to try instead.

For more common sildenafil warnings you can read our blog.

Who Should Not Take Sildenafil?

Sildenafil might not be right for some men with certain medical conditions. If you fall into any of the below categories, it’s best to speak to your healthcare provider about possible alternative ED medicines.

Men who have been advised by their healthcare provider not to participate in sexual activity due to their heart problems (pulmonary arterial hypertension/high blood pressure, heart disease or history of heart attack, for example) should not take sildenafil.

Sildenafil dilates the vascular system, which can cause sudden low blood pressure and may potentially be life-threatening.

Men who are currently taking medicines such as nitrates, alpha-blockers or antihypertensives for arterial hypertension should speak to their healthcare provider about potential drug interactions. Sildenafil can have a lowering effect on blood pressure when taken in conjunction with these medicines and can be very dangerous.

If you take recreational drugs with amyl nitrate and butyl nitrate (known as “poppers”), you should not take sildenafil. Taking recreational drugs containing nitrates in combination with sildenafil can cause your blood pressure to drop dangerously low.

Disclaimer: It is also dangerous to take sildenafil tablets at the same time as other ED medicines, such as Cialis®, Levitra® and Stendra®. Taking multiple PDE5 inhibitors at the same time can put you at risk for a dangerous drop in blood pressure.

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How to Take Sildenafil: Final Thoughts

Sildenafil is a great erectile dysfunction treatment for many men. However, before you take your first dose, there are a few things you should know about the drug, including side effects, who should not take sildenafil, and more.

If you’re interested in learning more about ED treatment with sildenafil and if it’s right for you, start a conversation with your healthcare provider. 

For more information on erectile dysfunction, check out our other blog posts.

4 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. Highlights of prescribing information: Viagra (sildenafil citrate). (2017, August). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020895s048lbl.pdf
  2. Viagra (sildenafil citrate) tablets. (2007, October). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/020895s027lbl.pdf
  3. Sildenafil. (2018, January 15). Retrieved from https://medlineplus.gov/druginfo/meds/a699015.html
  4. Smith BP, Babos M. Sildenafil. Updated 2022 Sep 19. In: StatPearls Internet. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558978/

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.