Viagra Dosage Guide: Strengths, Form, When to Use, & More

What Is Viagra (Sildenafil) & How Is It Used?

Viagra, or sildenafil, is a medication FDA-approved to treat erectile dysfunction. Viagra and other erectile dysfunction medications are known as PDE5 inhibitors. During sexual stimulation, nitric oxide (NO) is released locally in the penis, which allows the inflow of blood to form an erection. Viagra and other PDE5 inhibitors enhance the effect of nitric oxide, causing the erection to last longer. In the absence of sexual stimulation, Viagra has no effect at recommended doses.¹

Viagra Form & Strengths

Viagra is available as a brand or generic medication in tablet form. The dosages available are 25mg, 50mg, and 100mg.  You and your doctor will work together to determine the correct dose based on how well the medication works and how well it is tolerated by your body. If tablets are difficult to swallow, they can be crushed to allow for easier administration.¹ You may also find some compounding pharmacies have other forms available, like mints or liquids.

Viagra is available in the following form and strengths:

• 25 milligrams (mg) oral tablet
• 50 mg oral tablet
• 100 mg oral tablet

It is important to use medication exactly as prescribed. Viagra and other ED medications are intended to be used as directed, with specific limits on the amount taken and not more than once per day. Viagra should be used only as needed 30 minutes to 1 hour prior to sexual activity. Viagra can be taken with or without food.¹

Viagra Dosage for Adult Males with Erectile Dysfunction

Viagra is FDA-approved for erectile dysfunction in adults and should only be taken on an as-needed basis. It is not intended to be taken daily.¹

Here is Viagra dosage information for adult males with erectile dysfunction:

• Typical starting dosage: Most adults will start by taking one 50mg tablet. Some elderly patients will begin by taking one 25 mg tablet.
• Maximum dosage:  The maximum dose of Viagra is 100mg. In addition, the maximum daily dose is just one tablet of your prescribed strength.

Will My Viagra Dosage Increase Over Time?

Sometimes dosing is adjusted when you first start using Viagra, but when a stable dose is reached, it is not usually adjusted further. It is important not to increase the dose of Viagra on your own. This can lead to unsafe, unwanted side effects. If you feel the effect of Viagra is not enough or does not work as expected, speak with your doctor.

Viagra Dosage Considerations

The Viagra dose you take is based on your individual health conditions, other medications you take, and your age. Most often, your doctor will start you on a low dose to ensure the medication will be safe. It is important not to increase your dose on your own. Additionally, it is important to remember that the medication takes time to work. If you took the medication less than an hour ago, give it some more time for the medication to take full effect.

The most common reasons that the dose of Viagra will be different than usual is a person’s age, kidney or liver issues, or other medication taken at the same time. Often the dose is lowered to avoid unwanted and unsafe side effects.¹

Dosage for Adults Over 65 Years Old

The recommended starting dose for adults 65 and older is 25mg. This is because patients 65 years or older were found to have higher levels of Viagra in their blood after taking the same dose as others of a younger age. This can lead to more side effects and the medication working for too long.¹

Dosage for People With Kidney Problems

The recommended starting dose for adults with severe renal impairment is 25mg. Talk to your doctor if you have renal disease to determine if you should take a lower dose than normal of Viagra. Patients with severe kidney problems can have higher levels of Viagra in their blood after taking the same dose as others with normal kidney function. This can lead to more side effects and the medication working for too long.¹

Dosage for People With Liver Problems

The recommended dose for patients with any amount of liver disease is 25mg. When someone has reduced liver function from liver disease, Viagra stays active in the body longer than normal. This can lead to more severe side effects and longer-lasting effects.¹

Dosage Adjustments for Drug Interactions

In addition to health conditions, other medications can also change the recommended dose of Viagra. Some medications you take may have an effect on how Viagra works. It is also important to remember that Viagra can change the way other medications work as well. When you are prescribed Viagra, it is important to discuss all of your current treatments with your doctor. This can help to eliminate dangerous drug interactions and find the safest and most effective dose of Viagra.

The following table highlights some of the most common drug interactions. You should take the time to review your entire med list with your doctor or pharmacist to ensure you are taking the correct dose of Viagra.¹

Lead-in sentence: Medications that can interact with Viagra include:¹

Interacting Medication (condition treated)	Starting Viagra Dosage
Nitrates (dilates blood vessels)	Do not use
Alpha-blockers (urinary symptoms)	25mg or lowest possible dose
Amlodipine	Normal dose, monitor for low blood pressure
Ritonavir	25mg, a max of one dose in 48 hours
CYP3A4 inhibitors	25mg

Disclaimer: This is not an exhaustive list of potential interactions with Viagra. Make sure you tell your prescriber all medications or supplements you are taking so they can check for any potential interactions with Viagra.

How to Take Viagra

Viagra is taken by mouth with or without food. The best way to take the medication is only when needed, 30 minutes to 1 hour prior to engaging in sexual activity. It is very important never to take more than prescribed, never double up on a dose, and never take more than one dose in a 24-hour period. Unlike some other ED medications, Viagra is not meant to be taken daily. If you feel that you need Viagra more frequently, you should talk to your prescriber about other options.

What if I Miss a Dose of Viagra?

Since Viagra is an as-needed medication, it is not necessarily something that can be missed. If you begin engaging in sexual activity and have not taken a dose of Viagra, you can take a dose. Be aware that it may take 30 minutes to 1 hour to take full effect. Never double up on a dose of Viagra.

How Long Does Viagra Last?

Viagra usually lasts about 4 hours. It also normally takes between 30 minutes and 1 hour for Viagra to take effect. It is important to remember these time constraints when planning sexual activity. Since it is not safe to take more than one dose of Viagra in a day, you should make sure to plan sexual activity within 30 minutes to 4 hours of taking the medication.¹

Viagra Dosage FAQs

Viagra is a common medication, and many people have questions about who can use it or how to use it. The following is a selection of some commonly asked questions. Read through them to get a better understanding of Viagra and how to use the medication safely.

Here are some frequently asked questions about Viagra dosage:

• Is Viagra dosage based on age or weight? Viagra is dosed by age. If you are over 65 you will start with a lower dose than someone less than 65 years old.
• What is the dosage of Cialis vs. Viagra? The main difference between Cialis and Viagra is that Viagra is taken only as needed. Cialis is available in an as-needed dose and a dose taken daily.
• Is Viagra safe to take? Viagra is generally safe. Taking only the prescribed dose as directed and reviewing your full health history with your prescriber can help ensure you are using VIagra safely.
• Does a higher dose of Viagra work better? In some cases, if the starting dose of Viagra does not work as intended, your doctor may prescribe a higher dose. It is important to never increase your dose on your own without the supervision of a doctor. Taking too much Viagra can be dangerous.

Can You Overdose on Viagra?

Yes, it is possible to overdose on Viagra. Studies conducted to observe the effects of taking too much Viagra at one time showed that known side effects increased in likelihood and severity. It is important not to take more Viagra than prescribed by your doctor and never to take Viagra more than once a day. This can greatly increase your chances of an overdose.

Signs of an overdose on Viagra include:¹

• Headache
• Abnormal vision
• Dizziness
• Flushing
• Fainting
• Cardiovascular emergencies
• Changes in eyesight

What Should You Do If You Take Too Much Viagra?

If you or someone you know takes too much Viagra at one time, you should seek medical assistance immediately. It is important to seek care immediately to ensure the proper support for any symptoms that arise. You should also communicate, if possible, the amount of Viagra you ingested and at what time.

Questions to Ask Your Healthcare Provider About Viagra (Sildenafil) Dosage

Speaking with your doctor, psychiatrist, and therapist in depth before taking Viagra is an important step to using Viagra safely. Online psychiatry services may be a good option if you are not comfortable with your current provider or would prefer virtual care for a potentially sensitive topic. No matter the provider, spend time asking questions to fully understand the dose you have been prescribed. It is important to be open and honest with your provider to allow them to provide the best care possible.

Questions to ask your care team about Viagra dosage include:

• How long will it take for me to adjust to taking Viagra?
• Am I at risk for more serious side effects if I am already taking other anxiety /depression medications?
• What is the best dosage to ensure fewer side effects?
• Can I increase my dose if I feel it is not working well enough?
• Is there anything I should tell my therapist about this new medication?
• Should I take this medication every day?
• How long will the effects last?
• Will taking Viagra always cause an erection?
• What medications should I not take with Viagra?
• How can I lower the cost of a Viagra prescription?