LIMITED TIME OFFER NEW YEARsale

LIMITED TIME OFFER SAVE UP TO 95% OFF ED MEDS & PAY $2 PER TABLET.

Rex MD Logo
Explore Treatments

Start your online visit

Erectile Dysfunction

Weight Loss

Testosterone

  •  

Hair Loss

Premature Ejaculation

Insomnia & Sleep

Herpes Breakouts

Top Products

Resources

Have Questions?

Talk to live agent (Mon – Fri: 9:30am – 6:30pm EST).
(866) 294-3772

More questions? Visit our FAQ page

Erectile Dysfunction

Generic Viagra (Sildenafil)

Erectile Dysfunction

Generic Viagra (Sildenafil)

Treat erectile dysfunction with an affordable FDA-approved medication that has the same active ingredient as “name brand” Viagra, but costs significantly less.

Get Started Now
Free Rush Shipping
Save up to 95% Off with Generic Viagra®

Through Rex MD, a licensed healthcare provider can prescribe sildenafil or another ED treatment online, if appropriate. No in-person doctor visit needed. Plus, you’ll get your medication quickly and discreetly with free, rush shipping.

Get Started Now
Free Rush Shipping
Save up to 95% Off with Generic Viagra®

Meet sildenafil
  • The more affordable, generic version of Viagra
  • Flexible dosage options
  • Taken on an as-needed basis for satisfying sex

How to take it

Always take sildenafil as instructed by your healthcare provider. It’s typically taken about one hour before you plan to have sex. After about 30 minutes, its effects will kick in, and for up to four hours, you are able to get hard if you are sexually excited. If you take sildenafil after a high-fat meal, it may take longer for the medicine to start working.

Common sildenafil side effects

Potential side effects can include flushing, headache, nausea, dizziness, chest or arm pain, and, in rare cases, changes in vision or loss of sight. Seek emergency care right away if you have an erection that lasts longer than four hours or it becomes painful. Do not drink alcohol to excess (more than five drinks) while taking this medication.

Prescription products require an online consultation with a physician who will determine if a prescription is appropriate.

Why sildenafil?

While it has the same active ingredient as branded Viagra®, sildenafil (the generic version of Viagra) is about 95% cheaper.

Sildenafil can be taken as-needed to help men achieve optimal erectile function. It’s good for guys who don’t want to take a pill every day.

Get Started Now

Inhibits PDE5

Sildenafil works by inhibiting an enzyme called phosphodiesterase type 5 (PDE5).

Boosts blood flow

When PDE5 is inhibited, blood is able to move more freely to the penis.

Gets you hard

More blood flow allows for harder, longer-lasting erections with sexual stimulation.

Real Members. Real Reviews.

Rex MD® has been chosen by over 475,000 men.

Trusted by over 346,000 men.

  • Keir D., Rex MD® Patient

  • Jamal S., Rex MD® Patient

  • Alex A., Rex MD® Patient

  • Steve W., Rex MD® Patient

  • Brian M., Rex MD® Patient

  • Sylvester, Rex MD® Patient

  • Michael G., Rex MD® Patient

  • Noel R., Rex MD® Patient

Start My Consultation
Free Prescription + Free Rush Delivery

Why choose Rex MD?

Rex MD helps eligible patients get prescription ED medications like sildenafil quickly, discreetly, and affordable — right from home. No in-person doctor visit needed.

  • The best price per pill, guaranteed

  • Free online consultation

  • Branded and generic treatment options

  • Fast, free delivery

  • Ongoing support from our care team

Get Started Now

How to take sildenafil

Always take sildenafil as instructed by your healthcare provider. It’s typically taken about one hour before you plan to have sex. After about 30 minutes, its effects will kick in, and for up to four hours, you are able to get hard if you are sexually excited. If you take sildenafil after a high-fat meal, it may take longer for the medicine to start working.

Get Started Now
ⓘ Important safety information ›

How to get sildenafil online through Rex MD

Free online consultation

Answering questions about your symptoms and health history.

Personalized review

If appropriate, a licensed physician will prescribe a treatment plan that meets your needs.

Fast, discreet shipping

Your medication will ship out in discreet packaging within two days.

Ongoing support

Contact our team anytime to discuss your treatment and make adjustments, if needed.

Get Started Now

Frequently asked questions about sildenafil

What is generic Viagra?

Sildenafil is the generic form of “name brand” Viagra. It’s used to treat erectile dysfunction.

How does sildenafil work?

Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection.

Does sildenafil lower blood pressure?

Sildenafil relaxes arteries throughout the body, which can cause your blood pressure to decrease. This can cause mild increases in heart rate. Patients with low blood pressure should use sildenafil with caution.

Can women take sildenafil?

While some research suggests sildenafil may benefit women with sexual dysfunction, the FDA has not approved it for use in women. In some cases, a doctor can prescribe it for off-label use. Women should not take sildenafil or any other prescription drug unless it's been prescribed by their doctor.

What does sildenafil look like?

Unlike branded Viagra, which comes in a blue diamond-shaped pill, sildenafil (generic Viagra) comes in white round or oval-shaped pills.

Is sildenafil safe?

Sildenafil is generally safe as long as you take the recommended dose and follow the instructions of your prescribing healthcare provider. Taking more than the recommended dose of sildenafil puts you at risk for serious side effects, such as heart problems, vision problems, or permanent damage to the penis.

Can I take 200 mg of sildenafil?

The highest recommended sildenafil dose for treating ED is 100 mg per day. Doses of 150 mg or 200 mg would be considered off-label use.

How much does sildenafil cost?

With Rex MD, patients can get sildenafil (generic Viagra) for as little as $6 a pill.

Is sildenafil (generic Viagra) as effective as “name brand” Viagra?

Yes. Sildenafil works the same as Viagra, but it costs less.

How long does sildenafil last?

The effects of sildenafil usually last about four hours, giving you a large time frame where you can have sex with optimal erectile function.

How long does sildenafil take to work?

The effects of sildenafil typically kick in about 30 minutes after you take it. That means, you should be able to achieve an erection with sexual stimulation.

Can you take sildenafil with alcohol?

If you have taken sildenafil, excessive alcohol consumption (more than a few drinks) can increase your likelihood of experiencing symptoms such as dizziness, lightheadedness, fainting, flushing, headache, and heart palpitations. You should avoid or limit the use of alcohol while taking sildenafil, and use caution when getting up from a sitting or lying position.

Explore Our ED Medications

Branded Viagra®

From $96 per use

This is the branded version of sildenafil.

Get Started Learn more
ⓘ Important safety information ›

Generic Cialis (Tadalafil)

From $6 per use

Tadalafil is the unbranded, more affordable, generic version of Cialis. It is taken on an as-needed basis for planned intimate encounters.

Get Started Learn more
ⓘ Important safety information ›

Branded Cialis®

From $29 per use

This is the branded version of tadalafil.

Get Started Learn more
ⓘ Important safety information ›

Daily Generic Cialis (Tadalafil)

From $2 per use

This is the unbranded, more affordable generic version of Cialis Daily. It is taken every day to allow for spontaneous intimate encounters.

Get Started Learn more
ⓘ Important safety information ›

Rex MD is excited to announce the New
TestoRx Prescription Testosterone Therapy

TestoRx will be available in October 2024

Prescription Testosterone

Enter your info to be one of the first in line.

By submitting this form, you agree to receive recurring automated promotional and personalized marketing text messages (e.g. cart reminders) from Rex MD at the cell number used when signing up. Consent is not a condition of any purchase. Reply HELP for help and STOP to cancel. Msg frequency varies. Msg and data rates may apply. View Terms & Privacy.


Thank you! We'll email you as soon as TestoRX is available to the general public.

In the meantime, check out all of the Men's Telehealth Treatments and Save 95% Off with generic Viagra & generic Cialis today.

Important Safety Information

Erectile Dysfunction
Last Updated: Aug 15, 2024
Table of Contents
  1. Viagra
  2. Cialis
 

What Should You Know Before Taking Viagra?

Disclaimer: The information provided on this page is not a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns about your health, please talk to a doctor.

Contraindications

Do not take Viagra® or generic Viagra® if you:

  • take medicines called "nitrates" (such as nitroglycerin)

  • use street drugs called "poppers" such as amyl nitrate or amyl nitrite, and butyl nitrate

  • take any medicines called guanylate cyclase stimulators such as riociguat (Adempas)

  • are allergic to sildenafil, as contained in Viagra® and Revatio, or any of the ingredients in Viagra®. See the end of this leaflet for a complete list of ingredients in Viagra®.

What should I tell my healthcare provider before taking Viagra® or generic Viagra®?

To make sure Viagra® is safe for you, tell your healthcare provider if you have any of the following before you take Viagra® or generic Viagra®:

  • Have or have had heart problems such as a heart attack,irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure

  • Have had heart surgery within the last 6 months

  • Have pulmonary hypertension

  • Have had a stroke

  • Have low blood pressure, or high blood pressure that is not controlled

  • Have a deformed penis shape

  • Have had an erection that lasted for more than 4 hours

  • Have problems with your blood cells such as sickle cell anemia, multiple myeloma, or leukemia

  • Have retinitis pigmentosa, a rare genetic (runs in families) eye disease

  • Have ever had severe vision loss, including an eye problem called NAION

  • Have bleeding problems

  • Have or have had stomach or intestinal ulcers

  • Have liver problems

  • Have kidney problems or are having kidney dialysis

  • Have any other medical conditions

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Viagra® and generic Viagra® may affect the way other medicines work, and other medicines may affect the way Viagra® and generic Viagra® works, causing side effects.

Drug Interactions

Tell your healthcare provider if you take any of the following because these drugs interact with Viagra® and generic Viagra®:

  • Medicines called "nitrates"

  • Medicines called guanylate cyclase stimulators such as Adempas® (riociguat)

  • Medicines called alpha-blockers such as Hytrin® (terazosin HCl), Flomax® (tamsulosin HCl), Cardura® (doxazosin mesylate), Minipress® (prazosin HCl), Uroxatral® (alfuzosin HCl), Jalyn® (dutasteride and tamsulosin HCl), or Rapaflo® (silodosin). Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. In some patients, the use of VIAGRA® or generic VIAGRA® with alpha-blockers can lead to a drop in blood pressure or to fainting

  • Medicines called HIV protease inhibitors, such as ritonavir (Norvir®), indinavir sulfate (Crixivan®), saquinavir (Fortovase® or Invirase®), or atazanavir sulfate (Reyataz®)

  • Oral antifungal medicines, such as ketoconazole (Nizoral®) and itraconazole (Sporanox®)

  • Antibiotics, such as clarithromycin (Biaxin®), telithromycin (Ketek®), or erythromycin

  • Other medicines that treat high blood pressure

  • Other medicines or treatments for ED

  • Viagra® and generic Viagra® contain sildenafil, which is the same medicine found in another drug called Revatio®. Revatio® is used to treat a rare disease called pulmonary arterial hypertension (PAH). Viagra® and generic Viagra® should not be used with Revatio® or with other PAH treatments containing sildenafil or any other PDE5 inhibitors (such as Adcirca [tadalafil])

Ask your healthcare provider or pharmacist for a list of these medicines, if you are not sure.

Know the medicines you take. Keep a list of them to show to your healthcare provider and pharmacist when you get a new medicine.

Viagra Side Effects

What are the possible side effects of Viagra® and generic Viagra®?

Viagra® and generic Viagra® can cause serious side effects. Rarely reported side effects include:

  • an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis.

  • sudden vision loss in one or both eyes. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). It is uncertain whether PDE5 inhibitors directly cause the vision loss. Stop taking Viagra® and call your healthcare provider right away if you have sudden vision loss in one or both eyes.

  • sudden hearing decrease or hearing loss. Some people may also have ringing in their ears (tinnitus) or dizziness. If you have these symptoms, stop taking Viagra® or generic Viagra® and contact a doctor right away.

The most common side effects of Viagra® and generic Viagra® are:

  • headache

  • flushing

  • upset stomach

  • abnormal vision, such as changes in color vision (such as having a blue color tinge) and blurred vision

  • stuffy or runny nose

  • back pain

  • muscle pain

  • nausea

  • dizziness

  • Rash

In addition, heart attack, stroke, irregular heartbeats and death have happened rarely in men taking Viagra®. Most, but not all, of these men had heart problems before taking Viagra®. It is not known if Viagra® caused these problems.

Tell your healthcare provider if you have any side effect that bothers you or does not go away.

These are not all the possible side effects of Viagra® and generic Viagra®. For more information, ask your healthcare provider or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

 

What Should You Know Before Taking Cialis

Disclaimer: The information provided on this page is not a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns about your health, please talk to a doctor.

Contraindications

Who should not take Cialis® or generic Cialis®? Do not take Cialis® or generic Cialis® if you:

  • take medicines called nitrates (such as nitroglycerin)

  • use street drugs called "poppers" such as amyl nitrate or amyl nitrite, and butyl nitrate

  • take any medicines called guanylate cyclase stimulators such as riociguat (Adempas)

  • are allergic to Cialis® or any of the ingredients in Cialis®. See the end of this section for a complete list of ingredients in Cialis®.

What should I tell my healthcare provider before taking Cialis® or generic Cialis®?

To make sure Cialis® is safe for you, tell your healthcare provider if you have any of the following before you take Cialis® or generic Cialis®?:

  • Have or have had heart problems such as a heart attack,irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure

  • Have had heart surgery within the last 6 months

  • Have pulmonary hypertension

  • Have had a stroke

  • Have low blood pressure, or high blood pressure that is not controlled

  • Have a deformed penis shape

  • Have had an erection that lasted for more than 4 hours

  • Have problems with your blood cells such as sickle cell anemia, multiple myeloma, or leukemia

  • Have retinitis pigmentosa, a rare genetic (runs in families) eye disease

  • Have ever had severe vision loss, including an eye problem called NAION

  • Have bleeding problems

  • Have or have had stomach or intestinal ulcers

  • Have liver problems

  • Have kidney problems or are having kidney dialysis

  • Have any other medical conditions

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Cialis® and generic Cialis® may affect the way other medicines work, and other medicines may affect the way Cialis® and generic Cialis® works, causing side effects.

Drug Interactions

Tell your healthcare provider if you take any of the following because these drugs interact with Cialis® and generic Cialis®:

  • Medicines called nitrates

  • Medicines called guanylate cyclase stimulators such as Adempas® (riociguat)

  • Medicines called alpha-blockers such as Hytrin® (terazosin HCl), Flomax® (tamsulosin HCl), Cardura® (doxazosin mesylate), Minipress® (prazosin HCl), Uroxatral® (alfuzosin HCl), Jalyn® (dutasteride and tamsulosin HCl), or Rapaflo® (silodosin). Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. In some patients, the use of Cialis® or generic Cialis® with alpha-blockers can lead to a drop in blood pressure or to fainting

  • Medicines called HIV protease inhibitors, such as ritonavir (Norvir®), indinavir sulfate (Crixivan®), saquinavir (Fortovase® or Invirase®), or atazanavir sulfate (Reyataz®)

  • Oral antifungal medicines, such as ketoconazole (Nizoral®) and itraconazole (Sporanox®)

  • Antibiotics, such as clarithromycin (Biaxin®), telithromycin (Ketek®), or erythromycin

  • Other medicines that treat high blood pressure

  • Other medicines or treatments for ED

  • Adcirca® (tadalafil) is used to treat a rare disease called pulmonary arterial hypertension (PAH) and has the same active ingredient as Cialis®. Cialis® and generic Cialis® should not be used with Adcirca® or with other PAH treatments containing sildenafil or any other PDE5 inhibitors (such as Revatio® [sildenafil citrate])

Ask your healthcare provider or pharmacist for a list of these medicines, if you are not sure.

Know the medicines you take. Keep a list of them to show to your healthcare provider and pharmacist when you get a new medicine.

Cialis Side Effects

What are the possible side effects of Cialis® and generic Cialis®?

Cialis® and generic Cialis® can cause serious side effects. Rarely reported side effects include:

  • an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis.

  • sudden vision loss in one or both eyes. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). It is uncertain whether PDE5 inhibitors directly cause the vision loss. Stop taking Cialis® and call your healthcare provider right away if you have sudden vision loss in one or both eyes.

  • sudden hearing decrease or hearing loss. Some people may also have ringing in their ears (tinnitus) or dizziness. If you have these symptoms, stop taking Cialis® or generic Cialis® and contact a doctor right away.

The most common side effects of Cialis® and generic Cialis® are:

  • headache

  • flushing

  • upset stomach

  • abnormal vision, such as changes in color vision (such as having a blue color tinge) and blurred vision

  • stuffy or runny nose

  • back pain

  • muscle pain

  • nausea

  • dizziness

  • Rash

In addition, heart attack, stroke, irregular heartbeats and death have happened rarely in men taking Cialis®. Most, but not all, of these men had heart problems before taking Cialis®. It is not known if Cialis® caused these problems.

Tell your healthcare provider if you have any side effect that bothers you or does not go away.

These are not all the possible side effects of Cialis® and generic Cialis®. For more information, ask your healthcare provider or pharmacist.

Talk to your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What Happens if I Overdose?

Taking more than the recommended amount of Cialis® or generic Cialis® greatly increases your risk of side effects, including severe ones that can be dangerous, such as severe low blood pressure or an erection that won’t go away even after 4 or more hours (priapism). Never take more than the amount prescribed to you by your doctor. If you have any severe side effects after taking more than the recommended amount, or even after taking the amount of medicine prescribed to you, seek out emergency medical attention immediately.