Micropenis: Causes, Symptoms, Diagnosis & Treatment

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A micropenis is a penis that’s smaller than expected. It’s typically discovered in infancy or early childhood. The most common cause is fetal testosterone deficiency. In some people, early hormonal treatment can help stimulate penile growth toward a more typical length.

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Care at Cleveland ClinicPenile Disorders TreatmentFind a Doctor and SpecialistsMake an AppointmentContentsArrow DownWhat Is a Micropenis?Symptoms and CausesDiagnosis and TestsManagement and TreatmentOutlook / PrognosisPreventionAdditional Common QuestionsContentsArrow DownWhat Is a Micropenis?Symptoms and CausesDiagnosis and TestsManagement and TreatmentOutlook / PrognosisPreventionAdditional Common Questions

What Is a Micropenis?

A micropenis is a medical term for a small but normally structured penis. Something that affects your hormones or genes can cause this condition. Healthcare providers often diagnose it during the newborn to early childhood period.

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Micropenis is very rare. It affects about 0.6% of people worldwide. In the U.S., approximately 1.5 in 10,000 newborns have a micropenis at birth.

As long as you don’t have any other health conditions, a micropenis can function as expected — you can still pee and get erections.

Another name for a micropenis is a microphallus.

How big is a micropenis?

Healthcare providers determine micropenis size by the stretched penile length (SPL). The proper way to determine the SPL is to:

Gently stretch a flaccid (not erect) penis
Hold a measuring tape or ruler close to the body
Measure from the tip (glans) to the base of the penis

Providers diagnose micropenis if the length is less than 2.5 standard deviations below the average. For example:

The average SPL for adults is 5.25 inches (13.3 centimeters). An SPL of 2.67 inches (9.3 centimeters) or less indicates an adult micropenis.
The average SPL for a newborn is 1.4 inches (3.5 centimeters). An SPL of 0.75 inches (1.9 centimeters) or less indicates an infant micropenis.

Symptoms and Causes

What are the symptoms of a micropenis?

The most common micropenis symptom in a baby is a penis that measures less than 0.75 inches (1.9 centimeters) after it has been gently stretched. In adults, a penis that measures 2.67 inches (9.3 centimeters) or less after it has been gently stretched is a micropenis.

A micropenis can occur on its own. But it often occurs along with other health problems due to hormonal disorders or congenital urinary abnormalities. Your child’s symptoms will depend on the cause of their micropenis.

Some people who have a micropenis may have a lower sperm count (oligospermia). But this isn’t always the case.

What causes a micropenis?

The most common cause of micropenis is when there’s a testosterone deficiency during fetal development. This can happen due to many different conditions, including:

Male hypogonadism
Prader-Willi syndrome
Kallman syndrome
Androgen insensitivity syndrome

Male hypogonadism is the most common cause of micropenis. It occurs when your hypothalamus (the part of your brain that controls your autonomic nervous system and pituitary gland) doesn’t secrete the hormones that stimulate the testicles to produce testosterone.

Sometimes, there’s no clear cause for a micropenis.

Is it genetic?

Sometimes, a micropenis can result from a genetic variation. The SRD5A2 gene makes instructions for the steroid 5-alpha reductase 2 enzyme. The steroid 5-alpha reductase 2 enzyme helps convert testosterone to dihydrotestosterone (DHT), which is a type of androgen. DHT is important for the development of external genitals, including the penis.

Diagnosis and Tests

How is a micropenis diagnosed?

A healthcare provider can diagnose a micropenis during a physical exam. They’ll gently stretch your penis and measure it. They’ll then compare the measurement to the size range of your particular age group.

Management and Treatment

How is a micropenis treated?

The most common micropenis treatments include masculinizing hormone therapy (testosterone therapy) and penis enlargement surgery.

People of all ages can benefit from micropenis treatment. But the chances of success are greater if a healthcare provider diagnoses and treats the condition in infancy.

If your baby has a micropenis, their provider may refer you to a pediatric urologist or endocrinologist.

Testosterone therapy

The first line of treatment is usually a short course of testosterone. This therapy tests the ability of your penis to respond to the growth hormone.

A healthcare provider may recommend testosterone injections or testosterone skin gel. Penile growth is good in many infants who receive testosterone treatment. But providers aren’t sure whether the growth continues during puberty and adulthood. You shouldn’t try testosterone injections or skin gels unless a provider prescribes them.

Micropenis surgery

A healthcare provider may recommend penis enlargement surgery if you don’t respond to testosterone therapy. But if your penis functions and has adequate size, most providers won’t recommend surgery. This is due to the risk of complications and unrealistic expectations. Risks include:

Scarring
Infection
Pain
Loss of feeling (sensation) in your penis
Problems getting or maintaining erections (erectile dysfunction)

It’s important that you talk to a surgeon with lots of experience. They can ensure you clearly understand the risks and benefits of the procedure.

How long does it take to recover from micropenis surgery?

Your recovery time after penis enlargement surgery depends on several factors, including your health history and your body’s ability to heal. Most people can return to work, school and other typical routines in about four to six weeks. If you have a more physically demanding job, you’ll likely need to spend six to eight weeks recovering.

When should I see a healthcare provider?

Call a healthcare provider if your baby has a micropenis and they don’t respond to treatment or develop any new symptoms that affect their genital area.

If you’re an adult and have concerns about a micropenis, talk to a primary care provider. They can help diagnose micropenis, if necessary, and refer you to a urologist.

What questions should I ask a healthcare provider?

How will you diagnose micropenis?
If I don’t have a micropenis, is it possible that I have body dysmorphic disorder?
What treatment do you recommend to treat a micropenis?
What are the side effects of your recommended treatment?
Should I be aware of any other symptoms if I have a micropenis?

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Outlook / Prognosis

What can I expect if I have a micropenis?

The outlook depends on its cause. For example, people who have micropenises due to a hormone deficiency typically have a good outlook, especially with early diagnosis and treatment. They usually respond well to testosterone therapy at a younger age, gain adequate penile length and have typical penile function as adults.

Other disorders that cause micropenis, such as androgen insensitivity syndrome, can be more challenging to treat. Hormone therapy can’t treat a micropenis in these cases, and your penis may remain small.

How do people cope with having a micropenis?

Coping can be difficult if your penis doesn’t respond to early treatment. In all cases, talk therapy (psychotherapy) and social services can help you maintain good mental and emotional health.

Micropenis is a rare condition, and treatment depends on many factors. A healthcare provider will talk with you about your options every step of the way.

Does having this condition have a negative impact on sexual function?

Most people with micropenises have typical sexual function. A micropenis doesn’t affect your ability to pee (urinate), masturbate or reach orgasm.

A micropenis doesn’t have to be a barrier to sexual intercourse or intimacy. If penetrative sex is challenging, it’s a good idea for you and/or your partner(s) to talk to a sex therapist. They can recommend other ways for you to explore and enjoy intercourse with your partner. They can also work with you to overcome any stress or anxiety that you may feel.

Prevention

Can a micropenis be prevented?

You can’t prevent a micropenis. It usually develops because something affects a fetus’s hormones or genes before birth. But taking care of yourself before and during pregnancy can give your child the best chance for a healthy start to life. This includes:

Scheduling and attending regular appointments with a healthcare provider
Talking to a provider about the medications and supplements you’re taking
Taking a daily prenatal vitamin that contains at least 400 mcg (micrograms) of folic acid
Avoiding alcohol, tobacco and any drugs that a provider hasn’t prescribed

Additional Common Questions

What is the average penile length?

The average penis size for an adult is 5.25 inches (13.3 centimeters). The average penis size for an infant is 1.4 inches (3.5 centimeters).

A note from Cleveland Clinic

Many people are sensitive about their penises. A penis is important for urinary and reproductive functions. But many falsely equate their penis size with their masculinity. It’s important to remember penis sizes vary widely, and they don’t reflect your competence or worth as a person.

If your child has a micropenis — or you have concerns about your own penis size — talk to a healthcare provider. They can recommend treatment options. They can also refer you to a counselor or therapist who can help you overcome any anxieties that may be associated with a micropenis.

Care at Cleveland Clinic

When something’s wrong with your penis, you’ll want to get care right away. Cleveland Clinic’s experienced urology providers are here for you.

Cleveland Clinic doctor talking with male patient in the examination room.

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Last reviewed on 01/07/2026.

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References

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