Medicines – how do I know my medicines are working

Different medicines take different amounts of time to work.

Some medicines start working on the first day. These include medicines that treat high blood pressure, or medicines for pain and fever, like paracetamol. 

Some medicines can take longer to start working. For example, it might be 2–4 weeks before a cholesterol-lowering medicine like atorvastatin takes effect. And it may also take weeks before you feel the full effects of certain medicines, such as medicines to treat depression.  

You may be able to monitor your own symptoms to see if a medicine makes you feel better. Keeping a diary or a journal can help you to track when you've taken a medicine and any changes in symptoms you experience. 

If you're taking your medicine ‘as needed’, be sure to keep track of the time you take it and the amount of each dose.

If you start a new medicine and you get new symptoms or your symptoms get worse, contact your doctor right away.

Some medicines need careful monitoring with blood tests. This is done by the laboratory or doctor's office by taking a blood sample. 

For example, if you're taking warfarin, your INR level will be checked regularly to be sure the medicine and dose are working in the way they are expected to.

The test results will tell you and your doctor whether any changes are needed to make sure you are getting the treatment you need.

If you're concerned that a new medicine is not working in the time you've been told it should, talk with your doctor or pharmacist.

Don't stop taking the medicine without speaking to your doctor first. Some medicines need to be stopped slowly, over time, to prevent side effects or your symptoms getting worse. For example, suddenly stopping an antidepressant may make your symptoms worse.