Medicines – how do I know my medicines are working

When you start a new medicine, you may expect to start feeling the effects straight away. But some medicines can take time to make a difference. Here are some tips to help you know whether your medicine is working.

Find out about your medicine

Find out as much as you can about your medicine before you start taking it. Some things to ask your doctor or pharmacist include:

  • what the medicine is for
  • how to take it correctly so that it has the right effect
  • how long it takes for the medicine to make a difference
  • how to know if it is working or whether you need a test for this. 

For some medicines, such as allergy medicines, it's easy to see your medicine is working, because your allergy symptoms improve. But some  medicines are used for conditions where you don't notice the symptoms, such as to lower cholesterol, so you can only tell they are working with a blood test. 

Give it time

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.  

Keep track 

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.

Get tested if your doctor asks you to

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.

Get advice if a medicine doesn't seem to be working

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. 

Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 20 Oct 2020