Sorry to hear this .Please don't lose hope, but do fight for treatment and support in these times of scarce resources. Its not clear from your post if its the GP who has prescribed antidepressants. If so they need to push his referral through to a psychiatrist and camhs therapist, as he shouldnt really be on antids at his age without talking therapy according to NICE guidelines Monitoring medication in under 18s is important (see below from NHS website - this isnt to worry you, but for you to make sure he is being given the right help )
The use of antidepressants is not usually recommended in children and young people under the age of 18. This is because there is evidence that they can trigger thoughts about suicide and acts of self-harm in this age group.
Concerns have also been raised that their use could affect the development of the brain in children and young people.
An exception can usually only be made if the following points are met:
the person being treated has failed to respond to talking therapies such as cognitive behavioural therapy, and
the person being treated will continue to receive talking therapies in combination with antidepressants, and
the treatment is supervised by a psychiatrist (a doctor who specialises in treating mental health conditions)
If an antidepressant is recommended, then fluoxetine is usually the first choice.
Antidepressants ( which my DD also took in hospital) may help him feel well enough to respond to therapy and if he is given the tools in therapy to understand and cope better emotionally and has family/friends support, things can get better but it will take time.
If he is currently suicidal, please watch him closely and websites like papyrus, can help you with communication. www.papyrus-uk.org/help-advice/im-worried-about-someone/what-can-you-do-to-help-alert. Make sure you have emergency contacts at camhs. The important thing at the moment is to keep him safe. My DD was hospitalised. It was scary but did save her life, and meeting other young people struggling helped too.
The hope bit is that My DD took a year out of education , a little younger than your DS, but when she was well, she wanted to go back to college and is now at University, has lots of friends and is better equipped to understand and cope with her dips in mood , so he and you should know that many other teens take time out , and do return to their studies and full lives when feeling stronger.
Sorry this is long but know how much of a shock this is and hope the information is helpful. Depression,like any illness, can affect anyone at any time. Look after yourself too.