What dosage of antipsychotics should I be on? 

Your dosage means how much of your antipsychotic medication you should take, and how often you  should take it. Finding the best dosage for you will depend on a lot of factors. These include: 

  • The specific drug you’ve been prescribed. Safe dosages for different antipsychotics can vary  widely. 
  • Whether you’re taking other medication. Some drugs can interact with antipsychotics  if you take them around the same time. 
  • What you find works for you. Drugs work differently for everyone. Their effects may depend  on factors like your age, weight, genes, general health, liver and kidney function, and  whether you’re able to take the drug as recommended. 

You and your doctor or psychiatrist can work together to see whether your antipsychotic helps you  and how well it suits you. They should be able to tell you how the drug may help you, and when you  are likely to feel the drug’s effects. The aim should be to find a dosage where the benefits outweigh  any side effects. 

Remember: you have a right to know what dosage you have been prescribed, and why.

How can I work out my best dosage? 

  • You should always start at a low dose. For many people, low maintenance doses are as  effective as higher doses. The dose should still be enough for the medication to have an  effect. 
  • You should try taking the dose you’ve been prescribed for four to six weeks to see how it’s  working. 
  • Your doctor or psychiatrist may then adjust your dose gradually. But they should only do  this if you both agree it is necessary. 
  • You may find that your medication isn’t working, even if your dose is increased to the  recommended limit. Or you may find that your medication is causing unpleasant side effects  that are difficult to live with. In this case, your doctor or psychiatrist should consider offering  you a different antipsychotic drug
  • Your doctor or psychiatrist should clearly record any decisions about your medication in  your medical notes. This includes whether to start, continue, stop or change to another  drug. It is especially important if your doctor or psychiatrist prescribes a dose that’s outside  the usual recommended range for that drug. 

What are the effects of taking a higher dosage? 

The higher your dose, the more likely you are to experience problems with side effects. For example,  certain antipsychotics may cause side effects which affect your ability to: 

  • get up in the morning 
  • move your muscles naturally 
  • take part in everyday activities. 

Moderate to high doses of antipsychotics may also increase the risk of tardive dyskinesia. This is a  serious side effect which causes movements in your face or body that you can’t control. 

PRN prescribing 

PRN prescribing means giving you extra doses of your medication, in addition to your regular daily dose. ‘PRN’ stands for ‘pro re nata’, which means ‘as the circumstances require’ in Latin. So it only  happens in certain circumstances. 

You are most likely to be given a PRN dose if you are staying in hospital, either because:

  • the medical staff think you need a bit more medication in some situations, or
  • you’ve asked for a bit more medication in some situations. 

Any PRN doses should be carefully recorded in your medical notes. Your doctor or psychiatrist  should also monitor you to make sure that you don’t receive a daily dose that’s too high.

Is my daily dose too high? 

In most cases, antipsychotics aren’t licensed for use above the maximum recommended dosage  published by the Hospital Authority. But there are some situations where you may end up with a total daily dose  above the recommended maximum. These include: 

  • If your doctor or psychiatrist prescribes you a higher than recommended daily dose.
  • If you are taking more than one antipsychotic at the same time. 
  • If you are in hospital receiving a PRN prescription. This is the most likely situation in which  your daily dose may end up higher than the recommended limit. 

You have a right to know how much medication you’re taking in total, including PRN doses. If you  aren’t confident about working this out, your doctor, psychiatrist or pharmacist should be able to  explain it to you. 

If you are prescribed more than the recommended daily limit, your doctor or psychiatrist has a duty  to review this every day. But you can always speak to your doctor or psychiatrist if you feel your  daily dose is too high. You can ask them to review your dosage at any time, even if it is within the  recommended range. 

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