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Erectile dysfunction (ED) pills are usually safe to take. But they’re not all the same. Learn which safe ED pills to consider purchasing.

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Erectile dysfunction (ED) happens when you can’t achieve or keep an erection during sex. And it’s not uncommon: ED is thought to affect anywhere from 3–76.5% of men worldwide.

There are lots of options for ED pills, but not all of them are created equal. Even those approved by the Food and Drug Administration (FDA) can cause side effects or interact with other conditions that can make them unsafe for some people to use.

Read on to learn more about the ED pills that are FDA approved, what possible side effects to keep in mind, and where you can buy some of the safest ED pills available.

SildenafilVardenafilTadalafilAvanafil
Available since1998200320032012
Generic available?yesyesyesno
How long before sexual activity should you take it?30–60 minutes30–60 minutes30 minutes15–30 minutes
Lasts for4–6 hours5–7 hours24–36 hoursabout 5 hours
Strengths 25–100 mg2.5–20 mg2.5–20 mg50–200 mg
Typical starting does50 mg10 mg (5 mg for men over age 65)10 mg100 mg

Four ED medications have been vetted and approved by the FDA. This means that they’re generally safe to use, but they may still have some minor risks or side effects.

Sildenafil (Viagra)

Sildenafil (Viagra) is a type of ED medication called a phosphodiesterase type 5 (PDE-5) inhibitor.

When you get an erection, your body releases a protein called cyclic guanosine monophosphate (cGMP). This helps widen your blood vessels so that blood can flow into your penis and harden the soft, spongy tissues called the corpus cavernosa and corpus spongiosum.

The enzyme PDE-5 then breaks down cGMP and restricts blood flow to soften your penis — usually after you ejaculate.

But with ED, PDE-5 might break down cGMP too quickly and make it harder for you to get or keep an erection. PDE-5 inhibitors like sildenafil help slow down PDE-5 as it breaks down cGMP, making it easier to get hard and stay hard.

Most of the time, you’ll be able to get an erection between 30 and 60 minutes after taking a typical dose of about 50 milligrams (mg). Once it starts working, sildenafil lasts for about 4–6 hours.

Vardenafil (Levitra)

Vardenafil (Levitra) is also a PDE-5 inhibitor. It works in the same way as the other FDA-approved ED pills by helping increase blood flow into your penis so that your soft tissues can get and stay hard.

This medication is also sometimes used to treat pulmonary hypertension because of the way it works on the blood vessels in your lungs.

A typical dose of vardenafil — about 10 mg — takes about 60 minutes to start taking effect. If you’re over age 65, a healthcare professional might recommend that you take a lower dose of 5 mg.

Vardenafil lasts a little longer than sildenafil — about 5–7 hours per dose.

Tadalafil (Cialis)

Tadalafil (Cialis) is another PDE-5 inhibitor like sildenafil and vardenafil.

PDE-5 inhibitors can also affect nitric oxide (NO) in your body. NO is involved in helping relax blood vessels that allow blood to flow more easily into your penis.

Tadalafil is also sometimes used to treat benign prostatic hyperplasia (BPH), or enlarged prostate, because it helps relax smooth muscles in the prostate gland and bladder.

A typical dose of tadalafil is about 10 mg and starts working after about 30 minutes. In some cases, you may need to wait up to 4 hours before you start noticing the effects. After that, tadalafil can remain in your system for 24–36 hours before it stops working.

Avanafil (Stendra)

Avanafil is a newer form of PDE5 inhibitor similar to the other available ED medications. Unlike the other ED medications, there’s no generic version. So it might be a little more expensive than the others.

A single dose of about 50–100 mg usually starts working in about 30–45 minutes.

Most PDE-5 inhibitors are safe to take.

However, you’ll still want to discuss using them with a healthcare professional beforehand. This is because certain medical conditions can raise your risk of side effects. Additionally, certain medications can interact with ED pills and increase your risk of side effects.

Viagra can lower your blood pressure after you take it. It’s not a common side effect, but low blood pressure can have symptoms like fatigue, dizziness, and lightheadedness.

Low blood pressure can also be dangerous if you have heart disease. In addition, it can contribute to a heart attack or stroke if you’re also taking nitrates or riociguat (Adempas).

Cialis has a higher risk of side effects if you drink grapefruit juice or large amounts of alcohol.

Grapefruit juice can cause the levels of Cialis to get too high in your bloodstream, and alcohol can make it harder for you to get an erection. Cialis can also interact with nitrates or alpha-blockers for high blood pressure.

Nonprescription ED pills can be dangerous

The FDA and a 2016 case report warn that taking nonprescription, over-the-counter ED pills that aren’t FDA approved or prescribed by a healthcare professional can also increase your risk of side effects. They can also expose you to toxic ingredients that aren’t used in prescription ED pills.

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Chewable ED medications are also available as an alternative to pills. They typically contain the same ingredients as other ED pills, such as sildenafil, avanafil, tadalafil, or vardenafil.

Chewable ED medications are still just as safe and effective to take as regular ED pills. But they don’t always work as quickly or last as long because they need to be metabolized in your digestive tract.

ED pills are generally safe for most people to take. But there’s still some risk of side effects, including:

  • headache
  • flushing (reddish skin)
  • upset stomach
  • stuffy or runny nose
  • cold-like symptoms
  • nasal congestion
  • back pain
  • nausea
  • rash
  • heartburn

Seek immediate medical help if you experience any of the following severe side effects:

Your regular doctor can prescribe ED pills after an in-person visit. However, if you prefer, you can also get them online from a telemedicine company. They provide access to brand-name and generic versions of FDA-approved ED pills.

These retailers also offer medical services that can help you get in touch with a doctor who can walk you through the process, safety, and side effects of taking ED pills.

Although generic versions contain the same active ingredients to treat ED, some of the other ingredients may be slightly different based on the way different companies manufacture the pills.

Still, there’s no evidence that brand name ED pills work any better than their generic versions.

Vardenafil (Levitra) is thought to have the least side effects out of all the FDA-approved ED pills available.

Keep in mind that the side effects you experience might vary based on your overall health, other medications you’re taking, and your diet and lifestyle.

Viagra and all of the other FDA-approved ED pills are considered safe to take. But all of them are known to cause side effects in some people, especially at higher doses or when other medications interact with the ED pills.

Talk with a healthcare professional about what ED pill might be safest for you based on your overall health.

ED pills typically take between 30 and 60 minutes to start working.

This timing can vary depending on when you’ve eaten, how long it’s been since the last time you took an ED pill, and how aroused you are when you take it.

ED pills have a high success rate for most people.

But they may not work well — or even be safe to take — if you’re taking nitrates for chest pain or medications for high blood pressure.

ED pills may also not work if your ED is caused by conditions like anxiety that can result in ED even if you’re not experiencing any physiological issues related to your erections.

Research from 2021 suggests that all PDE-5 inhibitors are generally safe for people with diabetes to take.

Read more about ED and diabetes.

ED pill are generally safe for most people to take.

But keep in mind that they can have side effects. Talk with a healthcare professional before you start taking them. They can help make sure they’re safe for you, especially if you have any medical conditions or are taking any other medications that might cause side effects.