Using symptom checkers safely

Information on online symptom checkers – what they are, how they work and tips to use them safely.

Symptom checkers are online tools designed to help you understand what your medical symptoms could mean and guide you to the appropriate healthcare action.

How do online symptom checkers work?

Online symptom checkers are calculators that ask users to input details about your signs and symptoms of sickness, along with other information such as gender and age. Using computerised algorithms, the symptom checkers then give a range of conditions that might fit the problems you are experiencing. They can also advise someone whether to seek advice from a healthcare professional and the level of urgency with which to do so.

Examples of online symptom checkers

Note: The symptom checkers below are from other countries and may have information that differs from New Zealand recommendations. Also, the contact information for health service advice is not appropriate for New Zealand users. The New Zealand contact for health advice and information is Healthline phone 0800 611 116.

How safe and accurate are online symptom checkers?

As more people look online for their health information, the number of symptom checkers are growing. Currently the evidence for safety and accuracy of these is generally limited and where evidence is available, it is often of poor quality. Also, researchers have found that some mental health websites are either drug company owned or receive funding from drug companies and that they recommend medication more than sites not funded by the industry.1 This means it is important to also check who is providing the information the symptom checker is using.

Further, while online symptom checkers hosted on reputable health websites may have more value than a general internet search for symptoms, they are dependent on the information that the user provides and they can miss important information. Many symptoms checkers are from other countries and may have information that differs from New Zealand recommendations. Therefore, it is important to use online symptom checkers with caution.  

Tips for using online symptom checkers

Symptoms checkers are NOT diagnostic tools (they do not diagnose your illness), nor do they replace seeking medical advice or seeing your doctor. Rather, they give you a list of possible conditions and guide you to the appropriate healthcare action. Here are some tips for using online symptom checkers.

Do ()

  • Contact your doctor, nurse or pharmacist or call Healthline 0800 611 116 if you are concerned about your symptoms.
  • Write down questions to ask your doctor based on what you read when using a symptom checker. Read more about how to prepare for doctor's visits
  • Use an online symptom checker from a reliable source. This can be done by scrolling down to the bottom of a symptom checker’s home page to see if the site is HONcode certified 

Don’t (✘)

  • Rely on the symptom checker for a diagnosis. Symptom checkers are not diagnostic tools. 
  • Make changes to your medications.


  1. A literature review and meta‐analysis of drug company–funded mental health websites Acta Psychiatr Scand, 2013
  2. Beyond Dr. Google – the evidence on consumer-facing digital tools for diagnosis Diagnosis, 2018
  3. Evaluation of symptom checkers for self diagnosis and triage: audit study BMJ, 2015
  4. Online symptom checker diagnostic and triage accuracy for HIV and hepatitis C Epidemiol Infect. 2019 Jan
Credits: Health Navigator Editorial Team . Last reviewed: 23 Oct 2019