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Winstock A.R., Ford C., Witton J.
BMJ: 2010, 340, p. 800–904.
Unable to obtain a copy by clicking title? Try asking the author for a reprint by adapting this prepared e-mail or by writing to Dr Winstock at Adam.email@example.com.
A brief clinical review outlining the harms associated with cannabis use, and the optimal approaches for assessing and managing problem cannabis use in UK primary care.
Summary Two major diagnostic manuals recognise cannabis as a substance that can cause dependence. This is thought to happen in about one in ten users, and can be identified by a cluster of symptoms including: loss of control; inability to cut down or stop; preoccupation with use; neglecting activities unrelated to use; continued use despite experiencing problems related to use; and the development of tolerance and withdrawal.
No intervention to date has proved consistently effective for the majority of those with cannabis dependence, though trials in the United States and Australia support four methods of behavioural-based interventions: motivational interviewing; motivational enhancement therapy; cognitive-behavioural therapy; and contingency management. For younger users, evidence suggests family-based interventions may be the most effective.
In primary care, cannabis use can be initially raised as part of a discussion between practitioner and patient about healthy lifestyles, for example along with the issues of cigarette smoking, drinking, mental health, and sleep. Questions to identify potential problems could include:
• How long does a gram (or an eighth of an ounce) last you? How many joints a day do you smoke? How many joints do you make from a gram?
• On how many days a week or month do you smoke?
• Do you mix it with tobacco? Do you smoke cigarettes as well?
• Does your cannabis use cause you any problems, such as anxiety, a cough, interference with your sleep or appetite?
• Does your smoking ever interfere with what you want to do or what you have to do, such as working or studying?
• Have you ever thought about cutting down or stopping?
• Have you ever tried to cut down or stop? What happened? Were you able to sleep? Do you get irritable or moody?
• If you managed to stop for a while, how did you feel afterwards?
Asking the patient to draw up a pros and cons table can be good way to get them to think about their use, as can a motivational approach to explore and resolve ambivalence about cannabis use. If a patient’s cannabis use does not seem to be impairing their psychosocial functioning, the intervention can be restricted to giving health information and discussing risks.
Symptoms of withdrawal (eg, not being able to relax, and not sleeping as well) may be a barrier to stopping or reducing cannabis use. These can be more severe in people with overlapping mental health issues, or people who are also heavy cigarette smokers.
Guidance for managing withdrawal includes:
• Advising gradual reduction in amount of cannabis used before stopping altogether.
• Suggesting that the patient delays first use of cannabis until later in the day.
• Suggesting that the patient considers use of nicotine replacement therapy if he or she plans to stop cigarette smoking at the same time.
• Advising the patient on good sleep habits, including avoidance of caffeine, which may exacerbate irritability, restlessness, and insomnia.
• Suggesting activities that relax or distract the patient.
• Suggesting psychoeducation sessions for the user and family members on the nature, duration, and severity of withdrawal, to help with a better understanding of dependence and reduce likelihood of relapse.
• Advising the patient to avoid the cues and triggers associated with cannabis use.
Providing a patient with information about withdrawal symptoms may help them to prepare for discomfort, which if severe can be alleviated with a few days of symptomatic relief. For example:
• Prescribing short-term analgesia and sedation for withdrawal symptoms.
• If irritability and restlessness are marked, a very low dose of diazepam could be prescribed for three to four days.
Most dependent users do not require any drug intervention to manage their withdrawal.
For further reading, see the Effectiveness Bank hot topic “Cannabis is worth bothering with”.
Last revised 06 June 2017. First uploaded 01 June 2017
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