What You Need to Know About Penile Injections for Erectile Dysfunction

June 07, 2021

5 mins

When it comes to treating erectile dysfunction, most people think of Viagra® and Cialis® first, and for good reason. Since hitting the market in the late 1990s, just about everyone is familiar with these medications: they're effective and (now) cheap, despite the fact that most people have never taken them. 

About 50% of guys over the age of 40 will experience ED at some point, and even younger men are dealing with ED at higher rates. However, there are other effective ways to treat erectile dysfunction that are less common, and much more invasive. One of the most effective alternative treatments is called penile injection therapy. 

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What are Penile Injections? 

Just like the name suggests, with a penile injection, medicine intended to treat erectile dysfunction is injected directly into the penis. This therapy is not a treatment or cure for whatever may be causing the erectile dysfunction, it is simply intended to help the user achiever an erection firm enough for sex.

Penile injection therapy was originally used by accident. In 1977, a surgeon accidentally injected the vasodilator papaverine into the area around a patient’s penis. For the next two hours, the patient experienced a firm erection.

In 1982, a French surgeon noted a marked increase in blood pressure in the penis after it had been injected with papaverine. Considering that, an experiment was conducted in 1983 on 11 men experiencing erectile dysfunction. After a direct injection of papaverine to the penis, all of them reported having an erection firm enough for sex. Another decade of testing and research supported these claims, and the FDA approved penile injections as a treatment for erectile dysfunction in 1995. 

While penile injections are often not the first line of treatment for erectile dysfunction, overall the satisfaction with them is quite high. One survey found that over 70% of men that used penile injection therapy for eight years or more were satisfied with the results.

How Do Penile Injections Work? 

Penile injections work in a similar way to Viagra and Cialis. The medications in these drugs relax the smooth muscles and walls of the blood vessels located in the penis. This relaxation process allows them to dilate and expand, allowing for more blood to flow through these important arteries, and faster. 

By helping the penis to fill with blood and keeping the flow strong enough, an erection occurs. It should only take about five to 20 minutes after the injection to achieve an erection. 

In most cases, the erection happens naturally and spontaneously, though for many men it will require foreplay or stimulation. Depending on a few factors, such as dose and overall health, the erection should last between 30 and 90 minutes. It's also not uncommon for the erection to persist after ejaculation and orgasm. 

While it may take a few injections before discovering the right dose, it’s important not to inject any more than prescribed. Injections should only occur once every 24 hours and a generally no more than three times per week. 

Why Use Penile Injection Therapy?

Generally, the first line of treatment for ED is an oral prescription medication like Viagra (sildenafil) or Cialis (tadalafil). However, these medications are not 100% effective and have several negative interactions with other medications. As a result, penile injection therapy is often prescribed as a compelling second-line option.

Penile injection therapy is generally about as effective as oral medications. One published review of the medical literature found the effectiveness of these intracavernosal injections ranged from 54% to 100% in multiple experiments. When compared to oral medications, there are generally fewer side effects and complications with penile injections. 

The issue, and the reason you don't hear much about penile injections? Well, the obvious... The anxiety associated with using needles is high, with 65% of participants in the literature review reporting anxiety. Over time the anxiety declines as the injections become normalized, but an injection near the penis is a high hurdle for most guys.  

What Medicine is Used in Penile Injections? 

There are three different medications that are used for penile injections. Some prescriptions will include just one of them, but most prescriptions will be for a combination of all three. 

In general, doctors will first prescribe Trimix, which is a combination of three medications. They'll then make adjustments if needed. These medications are:

• Papaverine: Used since the early days of penile injection therapy, papaverine continues to be a leading medication. Sometimes used as a treatment for Alzheimer’s, multiple sclerosis, and asthma, papaverine relaxes the muscles of arterial walls causing them to dilate and increase the amount of blood flowing through them. 

• Phentolamine: This medicine has long been partnered with papaverine in order to enhance its effects. Phentolamine blocks the nerves that signal for the muscles in the arterial walls to constrict, allowing them to stay dilated for longer. It is sometimes used to treat high blood pressure and reverse the numbness of dental procedures.   

• Prostaglandin E1: Also known as alprostadil, this naturally occurring chemical is synthesized in the body in order to help muscle cells relax, expanding blood vessels. While the other two medications have been used for decades, this one has only recently started being used in the last few years. 

How Do You Perform a Penile Injection? 

Once you and your doctor have selected this method of treatment, your doctor should demonstrate the proper injection technique, detailed here by Memorial Sloan Kettering, a few times. There's a lot that can go wrong, so it's important to follow their directions carefully. It may take a while to get used to, but overall the injection process is fairly simple, with the needle into the flacid penis at a slight angle. 

What are the Side Effects of Penile Injections? 

Overall, the side effects associated with penile injections are fairly low, especially when compared to those associated with prescription medications. As with any injection, there is always a risk of experiencing bruising or bleeding around the injection location, but with proper needle placement and care this should be avoidable. 

The most common side effect reported is a mild or dull aching sensation after injection. Some of the other effects may include swelling or pain in the testes, bleeding or stinging in the urethra, and the development of scar tissue. 

The most serious side effect is priapism, a prolonged erection that doesn’t naturally go away. While it’s normal for an erection to persist, even after ejaculation, priapism can last for hours. Ice, taking sudafed, or taking a hot shower may help to reduce the erection, but if it lasts for more than four hours, immediate medical attention is advised. 

How Can Rex MD Help

Penile injections are generally not the first prescription for erectile dysfunction, but they can be as effective when first-line oral medications are not an option. The hurdle for most men is the injection, but the process is mostly painless and fairly easy. 

If you're dealing with erectile dysfunction, Viagra or Cialis will probably be your doctor's first suggestion. Both are available at affordable prices from Rex MD, prescribed online, if appropriate, and sent directly to your door. Get started with a free online consultation of your own by clicking here.