2 boys standing in front of a window

Child erection. How to explain them to kids

A common request that I receive from parents is about how to explain child erection. Their child may have started asking questions about why their penis grows bigger or harder. Or an older child may ask why their brother’s penis sometimes sticks out.

As a parent, child erections can be a challenge as we often associate erections with sex. So it is perfectly understandable if answering child erection questions can make you feel uncomfortable. As adults, we see an erection as a part of sex, and seeing your child’s erect penis or answering their questions about them, can feel awkward. Plus we often worry about whether we are giving them too much information, as many of us worry about whether their child actually ready to hear about sex.

So how do you talk to a child about erections, in an age-appropriate way?

Is child erection normal?

Child erection is completely normal. It is just one of those things that happens and shows that your child’s penis is working properly.  By ‘working properly’, I mean that their penis is capable of becoming erect so that when they are grown up, they can use it for the penetration part of sexual intercourse. Your child’s penis has been in ‘working order’ from the very beginning as a newborn. Some say that this was even happening when they were in utero, as a fetus inside your pregnant uterus.

So it is completely natural and healthy for your child to have erections throughout the day and night.

How does an erection happen?

Erections are all about an increased blood flow to the penis. The brain sends a chemical message to the blood vessels in the penis. The arteries relax and open to let more blood in. At the same time, the veins close, trapping the blood inside the penis. There is a lot of spongy tissue inside the penis. When it is filled with blood, that soft spongy tissue will go firm or hard, making the penis expand, because of all the extra blood inside it. The penis will become larger, firmer, and stand out from the body. It is now erect. When the erection is over, the veins will relax, letting the extra blood back into the body. At the same time, the arteries will close, only letting a small amount of blood into the penis. The penis then becomes soft again.

Why does my child have erections?

Child erections usually happen for no particular reason at all. We call these a spontaneous or involuntary erection ie when the penis becomes erect for no particular reason. Sometimes it can happen when they are overexcited during play or other intense occasions eg birthday parties. It can also happen when they have a full bladder and need to go to the toilet.

As your child gets older and goes through puberty, erections begin to happen more frequently because of sexual thoughts and feelings. Puberty is that time when the body starts to change into an adult body that is capable of reproducing. Which means that as well as being fertile and having an adult body, the brain also changes. Which means that for the first time, your child will start to have sexual thoughts and feelings, resulting in an erection.

They’ll still have spontaneous or involuntary erections that happen for no particular reason,  but these will now start occurring more frequently, often in the wrong place or time. And eventually, as they progress through puberty, spontaneous erections become less common.

Should you ever worry?

Usually, there isn’t anything to worry about. Child erection is usually completely natural and healthy.

 If your child’s erection lasts for more than a few hours or if you notice other unusual symptoms like rash, fever or discoloured skin, then you should seek advice from a health professional. Priapism, a painful erection that lasts 4 hours or longer, is rare in children but requires urgent treatment.

Phimosis is when the foreskin does not retract past the glans (head) of the penis ie the foreskin is tight. And in case you are wondering when the foreskin does retract, the proportion of boys with retractile foreskins is: 40% at 1 year, 90% at 4 years and 99% at 15 years.

You can read more about how to look after your child’s penis and foreskin from The Royal Children’s Hospital Melbourne’s Fact Sheet on penis and foreskin care.

If you are ever unsure, I am a firm believer in trusting your ‘gut instinct’. If your ‘gut instinct’ tells you there is something wrong, then seek advice from a health professional.

How to explain erections to your child

So how do you go about explaining erections to your child? There are a number of things you could say.

Let your child know that erections are normal and they happen to all boys (or kids with penises).

Make sure that your child knows that the part they are referring to is called a penis, and that when it grows hard (or bigger or however you want to describe it), that is called an erection.  You can read more about how to start naming the private parts of their body here.

An erection happens when extra blood goes into the penis. It means that their penis is working properly. You could also explain that their penis is practicing for when they are older and are ready to have sex.

As your child approaches puberty, you should let your child know that they will start to have more erections than usual and that they can happen at the wrong time and in the wrong place. This is also a good time to start talking about wet dreams, ejaculation and sexual feelings. If you’re unsure about how to start talking with your son about these things, then my parent book, Boy Puberty: How to talk about Puberty and Sex with your tween son.


The Sex Education Answer Book 728x90


There are some resources that may help with talking about child erections.  You can find some books and toys that will assist with naming the private parts of the body. You can find some educational websites for kids in my sex education resources list.

If you are unsure about how to answer your child’s questions, then my Q & A book, The Sex Education Answer Book, gives you by the age responses to tough questions kids ask parents about sex (for parents of kids aged 3 -14).

Amaze, an American sex education site that creates videos,  also has a video for tweens that explains ‘boners’.

You will also find other resources that will help you to talk about child erection on the blog.

Children’s Sexual Development and Behaviour – Pants Aren’t Rude by Pam Linke 2015.
From Diapers to Dating: A Parent’s Guide to Raising Sexually Healthy Children by Debra Hafner 2000.
Handbook of Child and Adolescent Sexuality; Developmental and Forensic Psychology edited by Bromberg & O’Donohue 2013.
Understanding Your Child’s Sexual behaviour: What’s Natural and Healthy by Toni Cavanagh Johnson 1999.
Where Do I Start? Supporting Healthy Sexual Development in Early Childhood by Family Planning QLD 2009.
Sexual development in Childhoood, editied by John Bancroft 2003.

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