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Can You Inject Sildenafil?

Dec 5, 2022
Can You Inject Sildenafil?

Sildenafil (Viagra generic) treats erectile dysfunction and pulmonary hypertension. It comes in a pill and intravenous form. The intravenous form is used when treating pulmonary high blood pressure or heart disease. For erectile dysfunction, sildenafil in pill form is the go-to option. Because sildenafil is available in a pill and intravenous form, you may question whether you can inject sildenafil or crush the pills to make it work quicker. The short answer is that it is not a good idea to do either.

How Does Sildenafil Work?

The sexual response in men has three phases: interest/libido, the ability to obtain and sustain an erection, and ejaculation/climax. Sildenafil is a phosphodiesterase 5 inhibitor (PDE-5). It stops the enzyme PDE5 from ending an erection. Here’s what happens:

  • Sexual stimulation triggers the sympathetic nervous system to release nitric oxide from nerve endings near blood vessels in the penis.
  • The blood vessels entering the penis dilate, which increases blood flow and causes an erection.
  • cGMP (another chemical in the cascade) levels must remain high to maintain the erection.
  • PDE5 inactivates cGMP, which ends the erection.
  • Sildenafil blocks PDE5, which helps maintain an erection.

By blocking PDE5, sildenafil helps keep nitric oxide levels high, which increases blood flow into the penis and sustains an erection. This option works for many men with ED. Men with damage to blood vessels from high blood pressure, diabetes, smoking, or high cholesterol may find sildenafil doesn’t quite help their ED.

Can You Inject Sildenafil?

How Do You Take Sildenafil?

Sildenafil comes in 25, 50, and 100 mg tablets. It is typically taken as needed approximately 30 to 60 minutes before sexual activity, although it may be taken up to 4 hours before. Men can comfortably take it earlier in the day without worrying about an unanticipated erection. Sildenafil doesn’t work unless the sympathetic nervous system is activated AND a man shows sexual interest.

Sildenafil’s effects last for about 4-5 hours. Consuming a high-fat diet can slow the medication’s absorption. Avoid taking sildenafil with grapefruit or grapefruit juice. Do not take sildenafil with other similar medications, such as avanafil (Stendra), tadalafil (Cialis), or vardenafil (Levitra).

Do not take sildenafil more than once in 24 hours.

erectile dysfunction medication

What Are Sildenafil’s Side Effects?

Do not take sildenafil with nitrates, guanylate cyclase stimulators such as riociguat, or other PDE-5 inhibitors.

Potential side effects and the percentage of people experiencing these side effects in clinical trials include:

  • headache (15.8%)
  • facial flushing (10.5%)
  • upset stomach (6.5%)
  • nasal congestion (4.2%)
  • flu syndrome (3.3%)
  • urinary tract infection (3.1%)
  • abnormal vision (2.7%)
  • diarrhea (2.6%)
  • dizziness(2.2%)
  • rash (2.2%)
  • back pain (2.2%)
  • joint aches (2.0)
  • other side effects reported less than 2%

Since sildenafil sustains an erection by blocking PDE-5, there is the potential for priapism, a prolonged, painful erection. Priapism is when blood fills the spaces in the penis and causes an erection but prevents the blood vessels from draining over time. When blood sits in the penis and fresh blood cannot enter it, oxygen levels may fall, causing tissue damage. Before taking sildenafil, talk to your doctor about the steps you should take if you experience priapism.

Sildenafil can also cause decreased blood flow to the optic nerve in the eye, causing vision changes and, in rare cases, sudden loss of vision. It is not clear whether sildenafil caused vision loss. People who experienced vision loss after taking sildenafil commonly also had heart disease, diabetes, high blood pressure, or high cholesterol or were smokers over the age of fifty.

Sildenafil may cause dizziness and altered vision. See how the medication affects you before driving or operating heavy equipment. Alcohol can lower blood pressure, worsening symptoms.

Will Sildenafil Work Faster Or Better If You Crush The Tablets?

To answer this question, researchers compared the bioequivalence of sildenafil tablets in pill form (not sustained release) with crushed sildenafil tablets in applesauce and an oral suspension. All three formulations worked the same, suggesting that there is no benefit to crushing a sildenafil tablet.1 The participants in this study were all fasting. A high-fat diet can slow sildenafil absorption. More research is needed to see if crushing sildenafil will mitigate the absorption delay.

Can You Dissolve Sildenafil (Viagra) In Water?

Researchers compared sildenafil as a suspension and an oral pill and measured plasma drug concentration. Both forms gave a similar drug concentration, suggesting that dissolving sildenafil in water might be an option for men who cannot swallow pills.1 This research was done under controlled circumstances with fasting volunteers. Some medication may be lost in the container after dissolving, causing a decreased dose. If you can swallow tablets, that is the preferred and tested way to take sildenafil.

Can You Use Viagra Intravenously?

Sildenafil injection (Revatio) is indicated to treat pulmonary hypertension (high blood pressure in the lungs) to improve exercise capacity. Revatio is administered as an intravenous bolus three times daily. According to, a 10 mg injection dose is predicted to have the same effect as a 20 mg oral dose. The intravenous form is commonly given until pulmonary hypertension is stabilized. Viagra should never be given intravenously at home unless under the close supervision of a medical professional.

erectile dysfunction

Can You Inject Sildenafil?

Intercavernous injections (penile injections) are a highly effective treatment for ED. However, sildenafil does not come in an injectable form, and it has not been tested for safety and efficacy in this form.

Sildenafil is a very effective oral treatment for ED.2 If you would prefer an injectable ED medication, consider Trimix. Trimix injectables are a combination of three different medications—phentolamine, papaverine, and alprostadil—that synergistically increase blood flow into the penis. 

Bimix is a combination of papaverine and phentolamine.

Quadmix combines papaverine, phentolamine, prostaglandin E1, and atropine. 

Read more: Trimix Injections for ED: The Risks and Benefits

Sildenafil is an effective ED treatment for many men. The preferred dosage method is swallowing the pill. There does not seem to be advantages to crushing the pill, and it’s dangerous for your health to inject the oral form of sildenafil.

Looking to get sildenafil? See how Invigor Medical can help today!

While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

Can You Inject Sildenafil?

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.


  • Gao X, Ndongo MN, Checchio TM, Cook J, Duncan B, LaBadie RR. A randomized, open-label 3-way crossover study to investigate the relative bioavailability and bioequivalence of crushed sildenafil 20 mg tablets mixed with apple sauce, extemporaneously prepared suspension (EP), and intact sildenafil 20 mg tablets in healthy volunteers under fasting conditions. Clin Pharmacol Drug Dev. Jan 2015;4(1):74-80. doi:10.1002/cpdd.146
  • Gong B, Ma M, Xie W, et al. Direct comparison of tadalafil with sildenafil for the treatment of erectile dysfunction: a systematic review and meta-analysis. Int Urol Nephrol. Oct 2017;49(10):1731-1740. doi:10.1007/s11255-017-1644-5


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