Are you worried about your teenager smoking pot? You're not alone - it's a problem you share with Prince Charles and Jack Straw - but what about the negative side-effects of cannabis use? Raisingkids.co.uk's guest expert, drugs counsellor Melissa Baxter, advises.

Raisingkids member's problem
My son, who is now 17, has been using cannabis for some time. He has now stopped smoking it (he says) due to chest problems and is now 'eating' it. He believes cannabis is harmless fun, but I don't! I am particularly concerned that this is contributing to his apparent short-term memory problems which have been identified at college. He admits that the cannabis probably isn't helping but chooses to continue. He is now suffering from glandular fever and I am concerned that cannabis will also contribute to the fatigue which I know can follow this condition. Do you have any advice for me?

Melissa's advice
Your son admits cannabis is interfering with his college work so does he really think it's 'harmless fun'? In a way, you're in a strong position as he seems to be fairly self-aware, willing to discuss his drug use and the negative side-effects with you. The challenge lies in getting him to take positive action.

Studies show most UK pot smokers start at 13-14 yrs-old and that long-term users learn to compensate for the undesirable side-effects. As with most users, your son seems to be aware that cannabis (also known as marijuana, pot, hash, spliff or skunk) makes him de-motivated.

I'd begin a conversation with him by asking outright 'Do you have a problem with using cannabis?' Don't be surprised if he says 'no'. Even if he's concerned about his marijuana use, it's hard to ask for help and it's rare for a young person to turn to their parents unless they are desperate. Teenagers often have their own support networks and will prefer to talk to their mates, or the school drugs worker, so don't assume he's ignoring the issues even if he doesn't want to talk to you about them. Review who your son is in contact with, in terms of college and youth services, and let him know that if it's hard for him to talk to you, you can let him know where he can find support.

Therapists are very aware of the stress that a child's drug use puts on parents. It's natural to be worried, guilty, or upset in this situation but try to admit that, as a parent, you can only do so much because... you're a parent.

It's good for a parent to be open when discussing drug use and related issues but remember to talk about cannabis in the context of other things that are going on in your son's life - talk about why A-levels are important to him, and his reasons for staying on after GCSE. Is it because all his friends are at college? Does he have older friends who are at university - and if so, are they enjoying it? Does your son want to go further?

Asking him why he wants to take his studies further will encourage him to talk about his ambitions and aims for the future, which will increase his motivation and could make him think '... well, perhaps I should reduce...' As a parent, your goal should be to encourage your son to make the decision to moderate or stop his cannabis use himself.

If he has problems giving up, www.marijuana-anonymous.org is an excellent support group, especially for teenagers. It provides online chat, information on where to get help in your local area, and is confidential - I'd recommend name-dropping Marijuana Anonymous and letting your son look it up on the net in his own time.

I'd also contact www.connexions.gov.uk. Connexions can put teens in touch with personal advisers, who offer information, advice and practical help with all sorts of things (like choosing subjects at school or mapping out future career options). Connections advisors can also help with anything which might be affecting young people at school, college, work or in their personal or family life - including drugs. Because it's a further education counselling service and not specifically for drug-users, there is no stigma attached and your son may feel more at ease about approaching a Connexions advisor than a 'drug counsellor'.

Unfortunately, families need to accept that most teenagers won't ask their parents for help. The good news is that, if you don't push it in their faces, the information offered will slowly sink in. Teenagers listen far more than they let on!

Finally, glandular fever is fairly common in young people and doesn't automatically develop into a long-term problem. It's unlikely that cannabis will speed your son's recovery - no drug, including legal ones, will be beneficial - but the most important things is not to drink alcohol until he has been given the all-clear, as glandular fever often affects the liver. Drinking lots of water or fruit juice, eating fresh fruit and vegetables, avoiding toxins, and resting as much as possible is the most sensible approach - if you have any concerns, consult your GP.