One in 10 young people will experience a mental health problem before the age of 15.

In your adolescence years – when you’re supposed to be only worrying about exams, first kisses, and how to smuggle your parents’ stolen gin on to the Year Nine residential trip – one in 10 teens are instead fighting uncontrollable urges to repeatedly check things, or feeling petrified at the thought of leaving the house, or scratching their arms open, or starving themselves, or even contemplating taking their own lives.

As if growing up wasn’t hard enough…

Many young people do recover from mental illness. But how do you recover from the trauma of going through that at such a key age? And, what if, after all your efforts to recover and be “normal” again… what if it comes back?

This is what I wanted to explore in my new book, Am I Normal Yet? The trauma of getting so ill so young, and the trauma of relapse. At the start of the book, my main character, Evie, has recovered from the OCD she feels robbed her of her early teen years. But, in her quest to catch up with what she’s missed out on, the pressure causes her to relapse.

When I’m not writing books, I work for a youth charity website, TheSite.org, and mental health relapse is something we deal with daily: the feeling that you’ve somehow let yourself down, that you’ve not been strong enough. The horrible fear that you’re going to have to start all over again…that maybe you’re always going to be like this.

There isn’t always a fairy-tale ending to mental illness. OCD can’t always be mended forever by a Prince Charming on a white horse, cradling a prescription for anti-depressants and a 10-week NHS course of cognitive behavioural therapy CBT. For every young person who makes a full recovery, there are those who will relapse. Who will tumble down the rabbit hole again. Who will feel crippling panic when Those Thoughts come creeping back. “It’s back, it’s coming back. I’m going to have to fight this all over again.”

Mental illness leaves a stain. Especially if you’re unlucky enough for it to strike in your formative years. It’s not just the exhaustive process of trying to remember all your coping strategies, to constantly fight the urge to indulge in behaviours you know are unhealthy and will quickly overtake your life but… oh, just for now they feel so good… It’s also overcoming the trauma that this happened to you in the first place. You! Nice you! Even though you’re a good person and you try hard and you never asked for this. This horrid, terrifying, wretched THING happened to YOU. And it’s completely, completely unfair. I wanted my book to be about mourning that fact. Because it’s totally OK to need to mourn it.

My favourite description of living with OCD came from one of the young girls I interviewed when writing the book. Diagnosed at 14, she was now 17 and “outwardly, living a normal life.” Yet, she told me the fight against her OCD never goes away, she’s always having to manage it. “It’s like whack-a-mole,” she said. “Just as I get rid of one compulsion, another shoots up to take its place. I used to be terrified of toilets and thought it was the worst thing in the universe. Literally, I would have given anything not to be scared of toilets. But I did CBT and chased it, and now I’m OK around toilets… but I’m scared of getting on trains. And I keep reminiscing about the toilets, and thinking, Oh, that toilet thing wasn’t so bad, I wish I still had that instead. Even though it was really, really awful.”

There are lots of incredible YA books out there about mental health, highlighting important issues in a responsible and sensitive way. I wanted to add relapse into the mix. Because I think it’s crucial to be honest with young people about mental illness. Relapse is nothing to be ashamed of. Relapse is part of recovery. Relapse, unfortunately, is something that can happen. If we’re going to break down barriers and reduce stigma, we’ve got to accept that not all mental health problems go away forever. Even if you’re doing everything “right”.

But that doesn’t mean you can’t live a good life – a full life – whatever the hell that means anyway. That you can’t be a hilarious person who compares OCD to “whack-a-mole”.

And that’s the other thing I wanted to achieve in my book. To let readers know that people with mental health issues can be FUNNY. In fact, lots are utterly hilarious, brilliant, clever humans, living good lives. They are so much more than their diagnosis.

Just as I wanted this book to be honest about the bad bits, I also wanted it to be honest about the good.

This article first appeared on ‘The Guardian’ on 2 August 2015.