Maria Pease
Article by: Maria Pease
Estimated 9 minutes read

Sildenafil is a prescription medication that helps to treat symptoms of erectile dysfunction, a condition that affects more than 30 million men in the United States. It works to improve blood flow when sexually aroused.

Sildenafil is the generic version of Viagra, the medication used to treat erectile dysfunction (ED). It's the most widely known medication in a class of drugs called Phosphodiesterase 5 (PDE5) inhibitors.

Sildenafil and other ED meds like it work by blocking the PDE5 enzyme. They also boost nitric oxide, a chemical in the body that helps the muscles in the penis to relax, allowing blood to flow to help you get and keep an erection when sexually aroused.

According to the Urology Care Foundation, about 30 million men in the US have issues with ED and sexual dysfunction. Erectile dysfunction is a health condition where even when sexually excited, the penis doesn't get hard or stay hard long enough for sexual intercourse. 

In this article, we'll discuss everything you need to know about sildenafil and why it can be a good option when considering testosterone replacement therapy.

What is Sildenafil?

Sildenafil is a prescription medication for treating erectile dysfunction (ED). It's the active ingredient in the branded Viagra® and is used to help a man get and maintain an erection long enough to enjoy sexual intercourse. (1)

As the first oral medicine for erectile dysfunction, sildenafil was patented in 1996 and was given FDA approval in 1998. It put ED on the map and soon became a big industry. 

In 2012, Pfizer's patents on sildenafil outside the United States expired, opening the door to other pharmaceutical companies to produce and distribute a generic version. While the color of the pills may differ depending on the pharmaceutical company, they all work the same way. (2)

How Does Sildenafil Work?

Strong erections are all about blood flow. When you become sexually aroused, the penis gets hard when the flexible and soft tissue fills with blood, so when enough blood isn't circulating, the penis can't get or stay hard, making it difficult to have intercourse. (3)

When the blood vessels are relaxed, they open up, allowing blood to circulate more easily. Still, sometimes the enzyme PDE5 can interfere with blood vessels dilating, which restricts blood flow to the penis, causing ED.

When you take sildenafil, it stops PDE5 from interfering with blood flow, temporarily allowing blood to flow to the penis so you can get an erection more easily and keep it long enough for sex. (4)

Discovering you may be having issues with sexual health and ED can be a concern. But chances are, it could be due to lower blood flow to your penis. When you don't have enough blood flow, you can't have an erection and may need to seek treatment from your healthcare professional.

How to Use Sildenafil Safely

Since sildenafil is a prescription medication, you'll use it under the supervision of your healthcare provider and will want to follow their recommendations. Generally, sildenafil can be taken with or without food anywhere from 4 hours to 30 minutes before sex. Do not take more than one pill in 24 hours.

Due to the possibility of interaction with other medications and supplements, it's essential to inform your medical practitioner of anything you're taking before starting sildenafil or any ED medication.

Interactions can change how the drug works and may make it less effective. Some medications are known to be dangerous to take with sildenafil, including nitrates such as nitroglycerin and guanylate cyclase. Both can cause blood pressure to drop to dangerous levels. (5)

Potential Side Effects of Sildenafil

Although considered safe for men's health when taken as prescribed, there are some side effects to be aware of when taking sildenafil. While they usually don't last long, they can be irritating. They include: (6)

  • Headaches
  • Stomach issues
  • Runny nose
  • Nose bleeds
  • Nausea and vomiting
  • Fever
  • Trouble sleeping
  • Erection lasting longer than a few hours

Some symptoms may be more serious and will need medical attention, so if you experience any of these symptoms, it's vital to seek emergency medical care. They include:

  • Shortness of breath
  • Symptoms of low blood pressure
  • Hearing loss
  • Ringing in the ears
  • Vision issues
  • Erection lasting 4 hours or more
  • Heart issues

Sildenafil vs. Other ED Treatments

Although sildenafil is a popular ED medication for sexual wellness, there are other medications you can consider, which all have pros and cons. These variations can include dosage, cost, frequency, and how long the drug lasts, all of which may influence your decision. Discussing these can help you and your doctor find the best fit. (7)

To clarify, all these medications have a generic version. 

Sildenafil (Viagra)

  • Sildenafil is taken 30 to 60 minutes before sex and stays in your system for about 4 hours. It comes in 25, 50, and 100 mg doses. How much you take will be determined by your medical practitioner. 

Pros: According to clinical data Sildenafil is effective for up to 82% of men with ED.

Cons: It may cause nausea, dizziness, and vision changes.

Tadalafil (Cialis®)

  • Tadalafil is taken 30 minutes before sex. It stays in your system for up to 36 hours and comes in a daily version of 2.5 and 5 mg to keep it in your system so you can be ready for sex whenever needed. It also comes in 10 and 20 mg, which you take on demand. 

Pros: It lasts longer, and food doesn't affect absorption.

Cons: It may cause limb pain, lower blood pressure, nausea and bowel discomfort. 

Vardenafil (Levitra®)

  • Vardenafil is taken 60 minutes before sex and remains in your system for 4 to 5 hours. Doses come in 5, 10, and 20 mg. With a recommended dose of 5 mg if you're 65 or older.

Pros: No known issues with nausea or other physical side effects.

Cons: It may take longer to work.

Avanafil (Stendra®)

  • Avanafil is taken 15 to 30 minutes before sex, comes in 50, 100, and 200 mg pills, and works for approximately 6 hours.

As you can see, various doses are available, and what you start with will depend on the medication and recommended dose. You can take Avanafil with or without a meal, but high-fat foods can lessen the effects. Take only once in 24 hours.

Pros: It works quickly in as few as 15 minutes and has few side effects.

Cons: No less expensive generic version is available.

To take medications like sildenafil for erectile dysfunction, you'll need to consult your medical practitioner and determine the best prescription. With such a variety that includes generic versions, one will most likely be right for you.

Regarding prices, generic versions are usually much cheaper. While insurance may help cover the costs, it may not cover them in full.

Low Testosterone and ED

Often, ED is an indicator of other medical conditions, such as diabetes and cardiovascular disease, which includes atherosclerosis (hardening or blocked arteries), heart disease and high blood pressure.

Added to this, low T can have a significant impact on your sex drive and the ability to get an erection. Low testosterone (low T) affects erectile ED in several ways:

  1. Reduced Libido: Low T levels can decrease sexual desire (libido), making it harder to get and maintain an erection due to reduced arousal.
  2. Blood Flow: Testosterone influences blood vessel health and nitric oxide production, which helps with penile blood flow. Low T can hinder this process, leading to ED from poor blood circulation.
  3. Body Changes: Low testosterone can cause muscle loss and increased body fat, impacting overall physical health and vitality and potentially affecting ED.
  4. Mood and Mental Health: Mood disturbances, like depression and anxiety associated with low T, can indirectly contribute to ED by creating psychological barriers.
  5. Overall Health: Low testosterone affects various aspects of men's health, including energy levels, bone density, and cognitive function, which can indirectly influence sexual performance.
  6. Type 2 Diabetes: This disease is common in people with low T and ED. Up to 75% of men with diabetes will experience erectile dysfunction (erection problems) in their lifetime.

Not all ED cases are due to low T, as ED can have multiple causes. Treatment options may include testosterone replacement therapy (TRT) and other treatments, depending on the specific circumstances and causes of ED. 

Is it safe to take ED meds and TRT together?

ED meds like sildenafil and, in particular, tadalafil daily can be taken with TRT. In fact, combined, they have other beneficial effects.

Taking both ED medications and TRT together can help address ED causes in men, especially those with conditions like type 2 diabetes, vascular problems, and obesity. Long-term testosterone treatment and lifestyle changes can often reverse some of the causes. Interestingly, studies have shown that Sildenafil (Generic Viagra®) can boost testosterone levels directly in men.

If you have symptoms of low T, such as low energy, low libido and weight gain, we suggest checking your testosterone levels and, secondly, having a medical consultation with one of our experts to see if TRT could help.


If you have symptoms of erectile dysfunction, sildenafil can help increase blood flow and erections for better sexual performance and improved sexual satisfaction. It's the generic version of Viagra and one of the most popular ED medications on the market. 

As with all medications, you'll want to discuss any other drugs or supplements you're taking to avoid medication interactions by talking to your doctor. If you are taking nitrates for a heart condition for example, you should not take ED medications, and it's important to always follow proper dosage guidelines. 

For a long-term solution to ED, looking at your lifestyle, testosterone levels, exercise routine and diet is essential. Concentrating on losing weight and improving overall health can help limit the risk and even improve erectile function. 

Man undoing a woman's bra. Red panties.

Don't let ED let you down!