Tylenol Won’t Raise Your Blood Sugar, but It Can Cause False CGM Readings

A continuous glucose monitor (CGM) is a device that monitors glucose (sugar) in your body’s tissues. CGMs help people better manage diabetes. But, in some instances, medications can affect their accuracy. These include common medications like Tylenol (acetaminophen) and aspirin as well as others like vitamin C and hydroxyurea.

If you have diabetes and use a CGM, it’s understandable that this may cause some concern. You may be wondering if common pain, fever, and cold medications like Tylenol raise blood sugar. The short answer is “no.” But they can cause false CGM results and, in turn, lead to management and safety problems. 

Let’s take a closer look at these medications and their possible effects on your CGM.

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How does Tylenol affect your glucose reading?

Tylenol doesn’t affect glucose levels, but it can affect CGM readings with Medtronic and Dexcom CGM systems. The same is true for all acetaminophen-containing products, including many over-the-counter (OTC) and prescription medications.

If the CGM device you’re using is sensitive to acetaminophen, it can incorrectly raise CGM glucose readings. This may vary person to person and also depends on your CGM device and medication dose (more on this below). 

If you know Tylenol can affect your CGM, be sure to:

• Check OTC medication labels before taking them.

• Avoid Tylenol when using an automated insulin delivery (AID) device.

• Check your glucose with a glucose meter (glucometer) when taking Tylenol.

• Test your blood glucose more often when taking Tylenol.

Should you avoid taking Tylenol before a glucose test?

No. Tylenol will not affect a blood glucose test result. Tylenol affects the way the CGM reads glucose levels, but it doesn’t affect how much glucose is actually in your blood and tissues. And it won’t affect the result you get from a lab blood test or a blood reading with a traditional glucometer. 

Can other medications cause a false reading on your CGM?

Tylenol isn’t the only medication that can interfere with CGMs and affect their accuracy. While device companies provide medication warnings, you may not know about all of them. 

If you wear a CGM, take precautions with these medications:

• Hydroxyurea: This medication is used to treat sickle cell anemia, and it can cause falsely high glucose readings.

• Vitamin C (ascorbic acid): Thiscan also falsely raise CGM readings depending on how much you take. Vitamin C is in multivitamins, supplements, and cold remedies. Most people get enough of it from a healthy diet. So taking it as a supplement may not be necessary. Sometimes, people need to take vitamin C as an injection to treat digestive problems (malabsorption) or extensive burns. But this isn’t common. 

• Salicylic acid: This is the active ingredient in aspirin. It may cause falsely low glucose readings. But salicylic acid doesn’t affect all CGM systems. So talk to your care team about whether this is something to consider. 

Some research suggests that other common medications and substances may have the potential to affect CGM readings: 

• Lisinopril: This is a common blood pressure medication.

• Albuterol: This is a common asthma medication.

 Ibuprofen (Advil) seems to be a safe alternative to acetaminophen and aspirin in terms of effects on CGM readings. 

Medications that affect Dexcom, Abbott, Medtronic, and Senseonic CGM systems

The effect a medication can have on a CGM depends on the type of CGM you’re using. The amount of medication you take can also affect the accuracy of your CGM. And the effect may vary from person to person. If in doubt, check your blood glucose with a glucometer before making any treatment decisions.

Let’s break down the medications you’ll need to be careful with according to the CGM brand.

Medications that affect Dexcom accuracy

The recommendations here vary depending on which Dexcom device you are using. 

Acetaminophen can affect the accuracy of:

• G4 Platinum and G5 Mobile CGM systems: Take acetaminophen with caution, it can cause falsely high glucose results. 

• G6 CGM system: You can take up to 1,000 mg of acetaminophen every 6 hours as normal. 

Hydroxyurea can affect the accuracy of:

• G4 Platinum, G5 Mobile, and G6 CGM systems: Do not use a Dexcom CGM while taking hydroxyurea — it can cause falsely high glucose results.

Medications that affect Abbott Freestyle Libre accuracy 

Again, advice varies depending on which Freestyle Libre device you are using. 

Vitamin C can affect the accuracy of:

• Freestyle Libre 14 day Flash Glucose Monitoring System: Taking vitamin C (no amount specified) may cause falsely high glucose readings.

• Freestyle Libre 2 and 3 Flash Glucose Monitoring System: Taking more than 500 mg of vitamin C per day may cause falsely high CGM readings.

Salicylic acid can affect the accuracy of:

• Freestyle Libre 14 day Flash Glucose Monitoring System, Freestyle Libre2, and Freestyle Libre 3: Taking salicylic acid may cause slightly low false glucose readings.

Medications that affect Medtronic CGM accuracy

The effect of medications may vary depending on the Medtronic CGM device you’re using.

Acetaminophencan affect the accuracy of:

• MiniMed 770G, MiniMed 670G, MiniMed 630G, and Guardian Connect CGM system: Take acetaminophen with caution, it can cause falsely high glucose readings.

• MiniMed 670G system: Be especially careful with “auto mode” on this device.

Medications that affect Sensionics CGM accuracy

Senseonicsis an implantable CGM device. Mannitol and tetracycline antibiotics can affect some of these devices.

Mannitolcan affect the accuracy of:

• Eversense® E3 implantable CGM system:Take caution with mannitol as an IV (intravenous) infusion and for peritoneal dialysis. It can cause falsely high glucose results.

Tetracycline antibioticscan affect the accuracy of:

• Eversense® E3 implantable CGM system: Take caution with tetracycline antibiotics, as they may falsely lower CGM glucose readings.

How to get an accurate CGM reading

When it comes to CGM accuracy, there are a handful of things to think about and troubleshoot. But your efforts are worth it. Your CGM can provide valuable insights and make everyday life with diabetes easier.

First things first. If the way you’re feeling isn’t matching your CGM values, check your blood glucose with a glucometer. You may have a false CGM result. This can be a temporary problem that corrects over time. Or there may be steps you can take to correct it. Each CGM system is different, so be sure to read your manual for details.

Other issues can also affect the accuracy of your CGM:

• Sensor issues: Your sensor may need calibration, or it may have been placed incorrectly. There can also be compression of the sensor area. This can happen if you sleep on the sensor or you wear a tight belt over it.

• Dehydration: This can happen if you haven’t had enough fluids or if you have an infection.

• Interference: This can happen from X-rays, CT scans, or MRI.

To improve CGM accuracy, make sure to:

• Stay well hydrated.

• Calibrate or change the sensor.

• Remove pressure from the sensor by changing your sleep position or tight clothing.

• Avoid medications that can affect the CGM sensor.

• Avoid exposing CGM equipment to radiation or strong magnetic fields. 

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Written by:

Jewels Doskicz, RN, BA

Jewels Doskicz, RN, BA, is an Arizona-based registered nurse with 22 years of hospital-wide clinical nursing experience and 11 years of medical writing and editing experience. She was a former healthcare content creator for a digital health tool at HealthLoop and director of clinical content operations at GetWellNetwork.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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