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Sildenafil is a drug for treating erectile dysfunction (ED). It is the active ingredient in Viagra and can help a person get and maintain an erection.

This article takes a closer look at sildenafil, ED, and how the drug works to relieve the condition.

People with ED have difficulty getting or maintaining an erection. It is a widespread condition, but many people find it difficult to discuss.

Sildenafil is a popular treatment for ED. The main ingredient in sildenafil is sildenafil citrate. The inactive ingredients include:

  • microcrystalline cellulose
  • anhydrous dibasic calcium phosphate
  • croscarmellose sodium
  • magnesium stearate
  • hypromellose
  • titanium dioxide
  • lactose
  • triacetin
  • artificial colors

Viagra is just one brand name option containing sildenafil. Other products might use different inactive ingredients.

Another brand name medication containing sildenafil is Revatio. In addition to treating ED, Revatio treats pulmonary hypertension (PH).

A person who wishes to use sildenafil for ED should contact a doctor, as the medication is available by prescription only in the United States.

Sildenafil falls into a class of medications called phosphodiesterase type 5 (PDE5) inhibitors. These inhibit phosphodiesterase enzymes, which degrade the molecules that relax the muscle tissue. This allows for increased blood flow, causing an erection.

Sildenafil does not cure ED. However, it can help treat the symptoms of the condition.

The pills come in strengths of 25 milligrams (mg), 50 mg, and 100 mg. People generally take a 50-mg pill approximately 1 hour before sex. Regardless of the dose, a person should not take sildenafil more than once per day.

The drug is fast-acting, and its effects typically last about 1 hour. It is important to note that sildenafil does not instantaneously produce an erection and that sexual arousal is necessary for the drug to work. Sildenafil also does not affect sex drive.

People are more likely to experience adverse reactions to the drug if they take more than the recommended amount.

Some common side effects of sildenafil include:

  • headaches
  • flushing
  • gastrointestinal distress
  • nausea
  • muscle aches and pains
  • dizziness
  • rashes

Other warnings

It is possible to take too much sildenafil. If a person overdoses on this medication, they should seek medical help immediately.

It is important to note that sildenafil is not a form of birth control, so it does not prevent pregnancy. Also, it does not protect against sexually transmitted infections.

People with concerns about sildenafil may wish to weigh the benefits and downsides of this treatment with a doctor.

Pros

  • it is widely available
  • it is noninvasive
  • can help with other medical conditions, such as PH
  • a more affordable alternative to branded ED medication
  • a doctor can adjust a person’s dosage as required

Cons

  • available only with a valid prescription
  • can interact with other medications, such as those for blood pressure
  • the effects do not last long, typically averaging 1 hour
  • it can cause side effects
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A person with symptoms of ED can take sildenafil if they first discuss it with a healthcare professional.

Sildenafil can also help those with pulmonary arterial hypertension. It works by relaxing and widening the blood vessels in a person’s lungs, which helps blood flow.

As sildenafil requires a valid prescription, a doctor will prescribe an appropriate dosage for an individual. A person should not take more than the prescribed dosage.

ED may sometimes be a sign of an underlying condition. For this reason, people should contact a doctor if they experience difficulty getting or maintaining an erection.

Some conditions that may cause ED include:

Learn more about the causes of ED.

If a person is taking nitrate medication that lowers their blood pressure, they cannot take sildenafil. This is because sildenafil can further lower blood pressure and cause serious side effects, such as life threatening hypotension.

Nitrate medication includes nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate.

Sildenafil is also unsuitable for people with heart conditions due to its effect on arteries. The drug stimulates the release of nitric oxide, which causes arteries to widen, lowering blood pressure. Although this is typically safe in a person with a healthy heart, it could be detrimental to those with heart conditions.

A person should ensure they take the correct dosage of sildenafil. If they take more than a healthcare professional describes, they should seek medical advice immediately.

Sildenafil binds itself to plasma in the blood, and the kidneys do not filter it out of the body as it does with certain other medications.

High doses of sildenafil increase the severity and duration of side effects. People may notice an increase in visual changes.

A person should avoid consuming large amounts of grapefruit when taking sildenafil. Consuming grapefruits or grapefruit juice can increase the levels of sildenafil in the body, causing the medication to be less effective.

Combining sildenafil with alcohol can also cause interactions. A 2019 study found that people who take sildenafil and other PDE5 inhibitors alongside alcohol can lead to:

  • indigestion
  • skin rash
  • headache
  • facial flushing
  • chest discomfort and palpitations
  • dizziness
  • altered vision
  • nasal congestion

People can use telehealth companies to buy sildenafil online. They will often need to answer health questions and have an online appointment with a doctor before they can get a prescription for sildenafil. Below, we look at the best places to buy sildenafil online.

Medical News Today’s methodology

Medical News Today chooses ED products that meet the following criteria:

  • Company reputation: MNT selects products from brands that have undergone internal vetting of medical and business standards. The brands we choose are reputable and reliable, with positive reviews and transparent business practices.
  • Product transparency: MNT selects products that state ingredients, side effects, and the recommended dosage clearly.
  • Safety: MNT selects brands that require a doctor’s prescription before customers can order Cialis. This ensures that a person can safely take Cialis and that the provider is responsible.
  • Price: MNT selects products that suit a range of budgets, including choosing brands that offer both brand-name and generic Cialis.

Medical News Today follows a strict product selection and vetting process. Learn more here.

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Please note that the writer of this article has not tried any of these products. All information presented here is purely research-based.

If a person cannot take sildenafil, wishes to avoid it, or wants to try something else, there are other options to treat ED.

Other PDE5 inhibitors include:

  • avanafil (Stendra)
  • tadalafil (Cialis)
  • vardenafil (Levitra)

Other treatment options include:

  • ED pumps
  • penile implants
  • penile injections
  • prescription testosterone

People may also wish to consider making lifestyle adjustments to help manage the symptoms of ED. These may include:

Mental health symptoms may also contribute to ED. Anxiety and stress about sex, for example, can make it more difficult for a person to get or maintain an erection. Talking with a mental health professional may help.

When a pharmaceutical company develops a new drug, it may have exclusivity for a specific period, which can last for years. Once this exclusivity period elapses, competitors are free to market generic versions of a drug.

Generic versions must contain the same active ingredients as the brand-name drug. The active ingredient is the element of a medication that makes it effective against whatever it is treating.

The Food and Drug Administration (FDA) allows differences in inactive ingredients, but drug companies must prove that they do not interfere with the drug’s function, effectiveness, or safety.

Viagra is the brand name version of sildenafil. Since its exclusivity period expired in April 2020, generic versions of sildenafil have been available from alternative drug companies. These are generally available at a lower cost.

One observable difference between Viagra (brand name) and sildenafil (generic) is the pill’s appearance. While Viagra pills are blue, sildenafil pills are white. Both medications are safe and effective.

A person should contact a doctor for a sildenafil prescription, as the drug is unavailable over the counter.

It is vital for a person to talk with a doctor if they take other medications, as these may interact with sildenafil. Medications that may negatively interact with sildenafil include those for blood pressure.

Anyone who experiences any of the following side effects when using sildenafil should contact a doctor right away:

Some other potential adverse reactions associated with sildenafil include low blood pressure and hearing loss.

Below are some common questions relating to sildenafil and ED.

What is the difference between sildenafil and Viagra?

Viagra and sildenafil contain the same active ingredient — sildenafil citrate. Viagra is the brand name version of sildenafil. Viagra is typically more expensive than sildenafil.

How often can you take sildenafil?

Prescribing information for Viagra states that people should take it 1–4 hours before sex. They should not take more than one pill a day.

Can you take sildenafil with other medications?

A person cannot take sildenafil if taking nitrate medication to treat angina or high blood pressure, as it can further lower their blood pressure. If a person takes sildenafil for pulmonary arterial hypertension, they cannot take any PDE5 inhibitors, including Viagra.

Individuals should not use sildenafil alongside other ED medications or devices. It is important to speak with a doctor before taking sildenafil to discuss potential interactions.

What happens if you take too much sildenafil?

If a person takes too much sildenafil, it can cause a persistent and painful erection. Other side effects may include blurred vision, hearing loss, and low blood pressure. If this happens, a person should seek immediate medical aid.

Does sildenafil get you hard?

Sildenafil can help a person get and maintain an erection with sexual stimulation.

How long does it take for sildenafil to kick in?

Sildenafil should typically begin working within 30–60 minutes after a person takes it. It can continue working for up to 4 hours.

Is sildenafil just as good as Viagra?

Viagra contains sildenafil as its active ingredient. As such, it will be equally effective.

Sildenafil is the generic version of the brand name drug Viagra. Sildenafil is an effective ED drug that is available at a fraction of the cost of Viagra.

Despite its status as a generic drug, it is just as safe and effective as Viagra. However, as with Viagra, it carries the risk of potential side effects and drug interactions.

People who experience ED should discuss their treatment options with a doctor.