Collagenase (Xiaflex) injections for Peyronie's disease

Xiaflex is a medicine made of enzymes (collagenase) that is injected into the scar plaque of Peyronie's disease to break it down. Combined with gentle stretching and bending called modeling, it can reduce the curve of the erect penis without surgery.

Also called Xiaflex, Collagenase injections, Collagenase clostridium histolyticum, CCH, Intralesional collagenase, Peyronie's injections, Plaque injections, Injections for a curved penis

Where: Clinic exam room
Anesthesia: Usually none; some doctors numb the skin or the base of the penis first
Time in the room: About 15 to 30 minutes per visit
Hospital stay: Home right after each visit
Back to normal: 1 to 2 days after each injection; bruising fades over 1 to 2 weeks
Back to work: Usually the same or next day

See the steps

PlaqueTunica albugineaErectile chambersUrethra

Where it happens. The highlighted part is what this procedure treats.

Overview

Peyronie's disease is a scar, called a plaque, in the tough sleeve around the erectile chambers of the penis. The scar does not stretch, so the penis bends toward it during an erection. The plaque is made mostly of a protein called collagen. Xiaflex contains collagenase, enzymes that break down collagen. Injected directly into the plaque, it weakens the scar so the penis can be stretched straighter.

In the United States, the Food and Drug Administration approved Xiaflex for Peyronie's disease in 2013. It is approved for adult men who have a plaque that can be felt and a curve of at least 30 degrees. The AUA guideline lists it as an option for curves between about 30 and 90 degrees in men whose erections are firm enough for sex, with or without ED pills.

Treatment comes in cycles. Each cycle has two injections given 1 to 3 days apart, then a stretching session in the clinic, then 6 weeks of stretching at home. You can have up to 4 cycles, about 6 weeks apart. In the large trials that led to approval, the curve improved by about a third on average, compared with about a fifth in men who got a placebo (an inactive injection). Most men get a straighter penis, not a perfectly straight one.

The main serious risk is a penile fracture, a tear in the erectile chamber, which is uncommon. Because of this risk, in the United States the medicine is given for Peyronie's disease only through a safety program (called a REMS) that requires doctors and clinics to be trained and certified. The same medicine is also used for a hand condition, Dupuytren's contracture.

The parts of your body involved

The penis has two erectile chambers, the corpora cavernosa, wrapped in a tough sleeve called the tunica albuginea. In Peyronie's disease a plaque forms in this sleeve, most often on the top, so the penis bends upward. The plaque is a firm patch of collagen, the same protein that makes up scar tissue elsewhere. The urethra, the urine tube, runs along the underside. Xiaflex is injected into the plaque itself, not into the erectile tissue or the urethra.

Plaque
A firm scar in the sleeve of the penis that does not stretch. This is where the medicine goes.
Tunica albuginea
The tough, stretchy sleeve around the erectile chambers.
Erectile chambers (corpora cavernosa)
Two spongy chambers that fill with blood during an erection.
Urethra
The urine tube on the underside. Xiaflex is not used when the plaque involves the urethra.
Nerves on top
Nerves that carry feeling to the head of the penis run along the top, near most plaques.

Why it’s done

Xiaflex is a way to reduce the curve without surgery. It suits men whose curve gets in the way of sex, whose erections are still good, and who would like to avoid or delay an operation.

A curve that interferes with sex
A bend of 30 to 90 degrees can make sex harder or uncomfortable for you or a partner.
Avoiding surgery
Injections are done in the clinic without anesthesia or incisions.
Limiting further shortening
Unlike plication surgery, which folds the longer side, injections work on the plaque itself and do not shorten the penis on purpose.
Good erections
Men whose erections are firm enough for sex, with or without ED pills, are the best fit. If erections are weak, an implant may be a better choice.

Other options

Watching and waiting
If the curve does not bother you or your partner, no treatment is needed. Many curves stay the same once the disease is stable.
Surgery
Plication or plaque incision with a graft straightens the penis more reliably, especially for large curves, hourglass narrowing or calcified plaques, with more recovery and some risk of shortening.
Penile implant
For men with weak erections as well as a curve, an implant corrects both.
Traction therapy
A device worn on the penis for hours a day gently stretches it. Evidence for a small benefit exists. Some doctors combine it with Xiaflex.
Other injections
Verapamil or interferon injections are sometimes offered. The evidence for them is limited.
Pills and vitamins
Most pills and vitamins tried for Peyronie's, such as vitamin E, have not been shown to straighten the penis.

Getting ready

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Before starting

Measuring the curve

Your doctor needs to see the erection. This is usually done in the clinic with an injection that causes an erection, so the curve can be measured with a protractor. Some doctors also use ultrasound to look for calcium in the plaque and check blood flow.

Checking the plaque

Your doctor feels for the plaque and checks that it does not involve the urethra. Plaques heavily hardened with calcium tend to respond less well.

Blood thinners

Tell your doctor about any blood thinner. Low-dose aspirin is usually acceptable. Stronger blood thinners raise the risk of bleeding and bruising and need a careful plan with the doctor who prescribes them.

The safety program

You receive a medication guide explaining the risk of penile fracture and the warning signs. Your doctor and clinic must be certified to give this medicine for Peyronie's.

Before each injection visit

Eat normally

No fasting is needed. You can drive yourself in most cases.

Wear supportive underwear

Snug briefs help hold any dressing in place and make the ride home more comfortable.

Plan around sex

You will need to avoid sex for at least 2 weeks after the second injection of each cycle. Plan with your partner.

The procedure, step by step

Press play or pick a step. Each drawing shows what your surgeon is doing at that moment. Your team may do some steps differently.

YouOperating table

1 / 8

1. Lying on the exam table

You lie on your back on the exam table. There is no general anesthesia. Some doctors numb the skin first; many find it is not needed because the needle is very fine.

You lie on your back on the exam table. There is no general anesthesia. Some doctors numb the skin first; many find it is not needed because the needle is very fine.
At the first visit, your doctor measures the curve during an erection, usually produced with an injection in the clinic. The angle is recorded with a protractor so progress can be tracked over the cycles.
With the penis soft, your doctor feels for the plaque and marks the point of greatest bend with a skin marker. This is where the medicine will go.
Using a very fine needle, your doctor injects a small amount of medicine into the plaque. The needle is moved slightly within the plaque to spread the medicine along it. It stings for a few seconds. The penis may then be wrapped gently, and you go home.
More detail
The dose for each injection is 0.58 milligrams of collagenase in a small volume. It is placed into the plaque itself at the point of maximum bend, taking care to stay out of the urethra and the erectile tissue.
You return 1 to 3 days later for the second injection into the same plaque. Bruising and swelling from the first injection are common by this point and are expected.
1 to 3 days after the second injection, your doctor gently stretches and bends the soft penis in the opposite direction of the curve. Each stretch is held for about 30 seconds, then released, and this is repeated a few times. It is uncomfortable but usually tolerable.
More detail
The enzyme has weakened the plaque by this point, so steady stretching helps lengthen the scarred area. Modeling is done gently and never forced.
At home you do two simple exercises. Three times a day, with the penis soft, you gently stretch it to its full length for 30 seconds. Once a day, if you have a natural erection without sexual activity, you gently bend it in the opposite direction of the curve for 30 seconds. Stop if it hurts or causes new bruising.
About 6 weeks after each cycle, your doctor checks the curve again. If it is still more than about 15 degrees and you would like more improvement, another cycle can be given. You can have up to 4 cycles in total, which is 8 injections.
More detail
Treatment stops early if the curve falls below about 15 degrees, if you are satisfied, or if your doctor feels more cycles will not help.

After the procedure

Right afterward

Right after the injection
Your doctor presses on the site for a few minutes. A light wrap may be placed and removed later that day.
Going home
You go home right after each visit. Most men can drive themselves.
Pain relief
Acetaminophen and a cold pack over your underwear usually help. Ask before taking ibuprofen or other pain relievers that can increase bruising.
Warning signs
Before you leave, your team reviews the signs of a penile fracture and tells you who to call.

At home

Bruising and swelling
Most men get bruising and swelling of the penis, sometimes spreading to the scrotum. It can look dramatic and usually fades over 1 to 2 weeks.
Pain
Mild to moderate soreness for a few days is common. A cold pack for 20 minutes at a time helps.
No sex for 2 weeks
Avoid sex and masturbation for at least 2 weeks after the second injection of each cycle, and until pain and swelling have gone. The plaque is weakest during this time.
Home modeling
Do the stretching three times a day and the straightening once a day for 6 weeks after each cycle. Be gentle. Do not do it during sex.
Be careful when sex resumes
When you start again, avoid positions or movements that bend the penis sharply. Stop right away if you feel a pop or sudden pain.
Traction or vacuum device
Some doctors recommend a traction or vacuum device between cycles. Use it only as your doctor directs.
Daily life
Showering, walking, work and most exercise are fine right away. Avoid activities that put pressure on the penis, such as cycling, for a few days.

Recovery timeline

Day 0
First injection
Curve measured, plaque marked, first injection given. Mild soreness that evening.
Days 1 to 3
Second injection
The second injection is given. Bruising and swelling usually appear.
Days 2 to 6
Clinic modeling
Your doctor stretches the penis 1 to 3 days after the second injection and teaches you home modeling.
Weeks 1 to 2
Bruising fades
Swelling and bruising settle. No sex for at least 2 weeks after the second injection.
Weeks 2 to 6
Home modeling
Daily stretching continues. Sex can resume once pain and swelling are gone.
About 6 weeks
Next cycle
The curve is rechecked and the next cycle can begin if needed.
About 6 months
After 4 cycles
A full course of 4 cycles takes about 6 months. The final curve is measured.
Long term
Next steps
If the curve is still a problem, surgery remains an option. Injections do not stop you from having surgery later.

What it feels like

Xiaflex treatment takes patience. The injections themselves are quick, but the course runs for months with regular stretching at home, and improvement comes gradually.

The first visit
Having an erection in a clinic so it can be measured feels awkward and embarrassing for most men.
What helpsDoctors who treat Peyronie's do this routinely. Ask the team to explain each step before it happens.
The injection
A quick sting and a feeling of pressure for a few seconds. Most men say it hurts less than they expected.
What helpsBreathing slowly and looking away helps. Ask about skin numbing if you are worried.
The bruising
Seeing the penis purple and swollen, sometimes with the scrotum too, can be alarming.
What helpsThis is expected and is a common effect of the medicine. It fades in 1 to 2 weeks. Call if swelling is sudden or very large.
The modeling session
Stretching a bruised penis is uncomfortable. Some men feel tense or anxious about it.
What helpsYour doctor will go gently and stop if it hurts too much. It is over in a few minutes.
The home routine
Stretching three times a day for weeks is easy to forget and can feel tedious.
What helpsSet phone reminders. Doing it consistently helps the result.
Waiting to have sex
Two weeks without sex after each cycle, repeated over months, can strain patience for both partners.
What helpsPlan the cycles around important dates. Talk openly with your partner about the timeline.
Checking progress
Improvement can feel slow, and some men are disappointed after the first cycle.
What helpsMost improvement builds over several cycles. Your doctor's measurements show change more clearly than looking at it yourself.

How well it works

In the two large trials that led to approval (called IMPRESS I and II), men treated with Xiaflex had their curve reduced by about 34 percent on average, about 17 degrees, compared with about 18 percent in men given a placebo. Men also reported being less bothered by the disease.

What to expect
Most men end up with a straighter penis, not a perfectly straight one. A curve that is reduced enough to make sex easier is a good result.
How it is measured
The curve is measured during an erection in the clinic, usually before treatment and after the final cycle.
Hourglass and dents
Xiaflex was studied mainly for curves. Its effect on hourglass narrowing or dents is less certain.
Length
Injections are not designed to add length. They do not shorten the penis the way plication surgery does.
If it is not enough
Surgery is still possible after Xiaflex if a curve remains that interferes with sex.

Risks

Every operation has risks. These are the ones people ask about most, with honest odds where good numbers exist. Your surgeon’s own results matter more than averages.

Common

Bruising and blood under the skin

Most men get bruising, and blood can collect under the skin of the penis. It usually fades in 1 to 2 weeks.

Swelling

Swelling of the penis, and sometimes the scrotum, is very common after each injection.

Pain

Pain at the injection site and with erections for a few days is common.

Blood blister

A small blister filled with blood can form on the skin. It heals on its own.

Less common

A lump at the injection site

A small, tender lump can form and usually softens over weeks.

Painful erections

Some men have painful erections for a few weeks after a cycle.

Itching

Itching of the genital skin can happen.

Larger blood collection

A larger collection of blood (hematoma) can form. Most settle without treatment; rarely one needs draining.

Rare

Penile fractureAbout 1 in 200 men treated

A tear in the erectile chamber, usually during sex or a sharp bend while the plaque is healing. Signs are a pop or crack, sudden loss of the erection, rapid swelling and dark bruising. It often needs surgery to repair.

Serious allergic reaction

Hives, swelling of the face or trouble breathing is rare and needs emergency care.

Injury to the urethra

Damage to the urine tube is rare when the injection is placed in the plaque.

Call your care team or go to the emergency room if

A popping or cracking sound or feeling in the penis, a sudden loss of erection, or rapid swelling and dark bruising: go to the emergency department now
Bruising or swelling that spreads quickly or becomes tense and very painful
Blood at the tip of the penis or trouble passing urine
Severe pain that does not ease with rest, cold packs and pain relievers
Hives, swelling of the lips, face or tongue, or trouble breathing (call 911)
Fever of 101°F (38.3°C) or higher, or spreading redness at the injection site

Questions to ask your surgeon

Is my curve and plaque a good fit for Xiaflex?
Does my plaque have calcium in it, and does that matter?
How many cycles do you expect I will need?
What results do your patients usually get?
Are you and this clinic certified to give this medicine?
What should I do about my blood thinner?
Can you show me exactly how to do the home stretching?
When is it safe to have sex again after each cycle?
Should I use a traction or vacuum device as well?
If the curve is still a problem afterward, what are my options?

Words you may hear

Collagenase: Enzymes that break down collagen. Xiaflex is a purified collagenase.
Collagen: A strong protein that makes up scar tissue, including the Peyronie's plaque.
Plaque: The patch of scar in the sleeve of the penis that causes the bend.
Tunica albuginea: The tough sleeve around the erectile chambers.
Treatment cycle: Two injections 1 to 3 days apart, followed by modeling in the clinic and 6 weeks of home modeling.
Modeling: Gently stretching and bending the penis to help lengthen the weakened scar.
Penile fracture: A tear in the erectile chamber, usually with a pop, loss of erection and fast swelling. It is an emergency.
Hematoma: A collection of blood under the skin.
REMS: A U.S. safety program (Risk Evaluation and Mitigation Strategy) that limits who can give certain medicines and requires training.
Intralesional: Injected directly into the plaque.
Placebo: An inactive treatment used in studies for comparison.

Common questions

Does it hurt?

The injection stings for a few seconds. The soreness, bruising and swelling over the next days bother most men more than the needle itself.

Will my penis be completely straight?

Usually not. On average the curve improved by about a third in the main trials. For many men that is enough to make sex easier and less bothersome.

Can I have it if my disease is still painful or changing?

The trials studied men with stable disease. Some later studies suggest it may also help earlier on. Your doctor will advise you based on your symptoms.

Why must I avoid sex for 2 weeks after each cycle?

The medicine weakens the plaque on purpose. For a short time the sleeve is more fragile, and a sharp bend during sex could tear it. Waiting lowers the chance of a penile fracture.

What does the safety program mean for me?

Because of the fracture risk, only certified doctors and clinics can give Xiaflex for Peyronie's in the U.S. You will get a medication guide and should know the warning signs. It does not change how the treatment is given.

Can I still have surgery later if it does not work?

Yes. Having Xiaflex does not stop you from having plication, grafting or an implant later.

Can Xiaflex fix an hourglass shape or a dent?

It was studied mainly for curves. Some men's narrowing improves, but results are less predictable. Grafting surgery is usually more reliable for hourglass narrowing.

Sources this page draws on

American Urological Association, Peyronie's Disease: AUA Guideline
U.S. Food and Drug Administration, Xiaflex (collagenase clostridium histolyticum) prescribing information and medication guide
Gelbard and colleagues, Journal of Urology, IMPRESS I and II phase 3 randomized trials of collagenase clostridium histolyticum for Peyronie's disease (2013)
European Association of Urology, EAU Guidelines on Sexual and Reproductive Health
Urology Care Foundation, Peyronie's Disease

Written November 2026. This page explains what usually happens. It is not medical advice and does not replace a conversation with your own surgeon, whose plan for you comes first.