How to deal with a Dexcom allergy

How do you deal with an allergic reaction to a Dexcom sensor when you want to wear a CGM?

Many Dexcom users suffer from allergic reactions, which make it difficult for them to withstand a sensor for 7 days or more. These allergies sometimes come and go, or suddenly show up after years of use with no trouble. There is a large online literature of forums posts and blogs that discuss issues and potential solutions. The present series of posts summarizes some of these online reports.

Caveat: it should be clear to everyone that allergies are highly personal issues. So what works for someone certainly may not work for another – it is everyone’s responsibility to do thorough investigation and testing of any option presented here or anywhere else before using it as a remedy. As always, this post (or any other on the forum) does not constitute medical advice.

Allergy to what?

There are two particular sources of allergies in the sensor. The most often seen is the adhesive pad – Dexcom describes it as “a pressure sensitive acrylic adhesive coated on top of a polyester spun lace fabric. The housing is attached with cyanoacrylate glue from Loctite. Both are medical grade materials. There is no latex or bovine components in the adhesive.” The second is the sensor probe itself. Dexcom has mentioned the presence of a small quantity of nickel, a common allergen.

How to figure out if you are reacting to the sensor fiber or the adhesive

Conduct a simple experiment: wear a Dexcom sensor for a few days without injecting the probe. If you still react to it, you are allergic to the adhesive.

Note: there is a very small likelihood that you may be allergic to both.

CGM and pump allergies: similarities and differences

There are great similarities between CGM and pump allergies. For both types of medical equipment, the PWD may be allergic to the sensor probe or the canula, and the adhesive pad. So the general strategies are the same. But, for every PWD, because the materials in pumps and CGMs and the adhesives are not the same, the actual remedy will likely be different for your pump and for your CGM. In fact, you may react to one and not the other (or, hopefully, to neither).


As always, the symptoms vary. Some of them may be:

  • red rash under the adhesive patch location, sometimes nicknamed “Dexcom rash” online.
    This aggressive-looking rash should not be confused with the little red marks you get after lifting a Dexcom sensor patch a bit too fast. The red rash can look quite angry, as it does on little Caleb’s skin. Such a rash takes multiple weeks to heal, and makes it very difficult to find enough sites to rotate a sensor through.

  • systemic reaction
    The localized reaction to spread to the whole body, involving a puffy face, wheezing, skin breakouts in multiple locations, and, worst of all, the risk of anaphylactic shock. Little Henry suffered such a systemic reaction :frowning: . A systemic reaction can quickly turn deadly: you should seek medical attention immediately.

  • Infection
    Localized rashes easily get infected. Such infections can be very serious for diabetics: PWDs are susceptible to infections because sugar is a great medium to grow bacteria. They are also more vulnerable to the consequences of infection because of the out-of-balance BG resulting from medical stress. With PWDs, such infections can quickly become deadly. Isabella suffered from such an infection.

First thoughts

It should be clear to all that, for anything but the mildest symptoms, consulting a dermatologist could be really helpful, and may well be necessary (although, unfortunately, possibly not sufficient). If you are normally subject to allergies, before starting on CGM, it may be a good idea to ask the rep about your known allergies, and to sample a couple of sensors. For instance, our endo clinic offered, as a standard, the opportunity to wear one for a week.



Sensor probe allergy

Allergy to the sensor probe itself appears to be less common than allergy to the pad adhesive – a good thing, since it is much harder to deal with. There is simply no way to avoid contact with the probe. So possible remedies can only mitigate rather than suppress. Three primary strategies are mentioned:

  • never using a skin area that has not fully recovered from a previous sensor application: using unblemished, fully recovered skin is critical

  • more frequent site changes: once the skin starts reacting, it takes a long time to get it to heal, and to avoid it reacting faster the next time around in this (or possibly other) location. One strategy is to change site the moment an allergic reaction is detected. This may result in changes more frequently than the usual 7 days. You may be able to discuss the issue with your prescribing physician and obtain a prescription and insurance agreement for more sensors.

  • use of a topical anti-allergy medication (unlikely to meet great success since the probe is under the skin), or of a systemic anti-allergy medication such as cetirizine (Zyrtec/Reactine). A prescription allergy medication may be required.



Adhesive allergy: simple steps

In mild cases, which are the most common, taking a few simple steps is enough to solve the problem. Some possible solutions are (use only those steps you need):

  • never apply a sensor pad to a skin area that has not fully recovered from a previous sensor application

  • do not use alcohol to clean the skin but antibacterial soap and water

  • use an adhesive barrier such as SkinTac, IV Prep (caution: it has alcohol), Skin Prep, Bard’s Barrier Wipe, Cavilon film or Cavilon cream, before applying the sensor pad. If you do so, make sure to (a) apply the SkinTac in multiple layers, letting the previous layer dry to tacky to the touch before applying the next one, and (b) leave a small area free of SkinTac where the actual sensor fiber will pierce the skin. Depending upon circumstances, we use either SkinTac bottle or SkinTac wipes. To make sure we don’t apply the barrier where the sensor will come through the skin, we typically draw a circle with a pen on the skin once it has been washed and dried.

  • use a squirt of OTC fluticasone such as Flonase (a hydrocortisone spray) after cleaning the skin and before applying an adhesive barrier or the Dexcom sensor pad. Others have reported success asking for an asthma inhaler prescription and using it as a skin spray, or using a Benadryl spray.

  • use a systemic anti-allergy medication such as cetirizine (Zyrtec/Reactine). A prescription allergy medication may be required.

  • don’t forget to thoroughly clean the skin after taking out a sensor



Adhesive allergy: additional adhesive layer

If simple steps don’t work, the next step is to place an alternative adhesive layer underneath the Dexcom sensor pad which is creating the problem, so as to only subject the skin to the alternative adhesive. The key is to find the right adhesive, which will not generate a similar allergic reaction. These adhesives are discussed in an upcoming wiki on Dexcom adhesives. Popular adhesive layers include:

In this case, the application sequence might be:

  • pick an area of skin fully recovered from previous sensor insertions

  • clean quickly with alcohol to remove oil from skin (those whose skin reacts to alcohol should skip that step)

  • clean skin with warm water and mild antibacterial soap.

  • dry thoroughly. Do not use a used towel (only a clean cloth towel, a clean paper towel, or air).

  • apply multiple layers of adhesive barrier (see above).

  • apply alternative adhesive layer, cutting out a small window where the sensor will insert through skin (depending upon the actual alternative layer, some users do insert the sensor straight through the adhesive layer without cutting an opening).

  • apply sensor on top of alternative adhesive layer. it may be useful to apply SkinTac or equivalent prior to applying the sensor, or to drench the sensor layer with SkinTac (or both), to improve adhesion.

  • don’t forget to clean the skin well and remove adhesives on skin after getting rid of sensor.



In the case of a serious allergic reaction that has not been contained by more prosaic precautions, we enter a domain where experimentation and substitution of multiple possible steps is likely necessary. Many sufferers have posted reports of their own trials. The following steps have seen success in the past.

Cut down the sensor pad area

Decreasing the total adhesive area of the Dexcom sensor will decrease the potential allergy risk. By cutting down on the adhesive area, you also decrease the adhesive power, so it will be important to do everything possible to boost adhesive capabilities of the final assembly. One particular difficulty is dealing with water (shower, or, worse, swimming): drying the assembly with a hair dryer after every exposure to water may be necessary.

Two layers of alternative adhesive

Some people have reported success by using two successive layers of the same alternative adhesive. In that case, it may be useful to use SkinTac or an equivalent adhesive under the second layer as well, and under the Dexcom pad. As for a single layer, make sure to cut out an opening for the sensor through both layers.

Hydrocolloid dressing instead of alternative adhesive

Many people report success with the use of a hydrocolloid dressing such as J&J Tough Pads to isolate the skin from the Dexcom pad adhesive. Again, it may be a good idea to apply SkinTac to the top of the hydrocolloid dressing, in multiple layers, prior to applying the sensor pad, or to drench the sensor pad with Skintac once it is on. Some people cut out a small window for the sensor to come through, while others insert the sensor through the Tough Pad.

At the moment (9/2017), J&J Tough Pads, the most popular and cost-effective of hydrocolloid dressings, appear to be unavailable for some unclear reason. Many alternative hydrocolloid dressings are available, typically for a higher cost :frowning: . Some of them include Tegaderm hydrocolloid dressing #90001, Tegaderm thin hydrocolloid dressing #90021, or CVS Hydrocolloid Bandages. It is possible to cut these dressings to size. It is sometimes necessary to trim the Dexcom sensor pad in order to fit the thick part of the dressing.

Layer of alternative adhesive below a hydrocolloid dressing

If lesser options are unsuccessful, it is possible to use a first layer of alternative adhesive, chosen among those that do not generate an allergic reaction, followed by a hydrocolloid dressing below the sensor pad. As usual, judicious use of SkinTac or another adhesive barrier is recommended between layers.

Adhesive remover

Once the sensor is done, an adhesive remover makes removal easier, causes less damage to the skin, and leaves less residue on the skin afterwards. Adhesive removers that people have used with success in the past include SkinTac Tacaway remover, Uni-Solve, Smith & Nephew Remove (for fragile skin, with aloe), J&J baby oil, Neosporin ointment (I can’t imagine this is a good idea but several people seem to swear by it), and Goo-Gone (true!). Several of these come in convenient wipes, and can also be used to remove the adhesive residue on the skin once the sensor has been removed. Rachel Morgan uses calendula oil for little Henry to clean up residue after the sensor is off.

After completing residue removal, don’t forget to thoroughly wash the area with warm water and a mild soap.

Post-removal skin treatment

To improve skin healing and regeneration and prevent future reactions, some report using different substances on the sensor pad site once the pad has been removed. One popular option is prescription hydrocortisone cream or spray.



Good adhesion: keeping the sensor on for 7 days or more

Many of the practices required to mitigate or suppress allergic reactions to the adhesive pad result in lessened adherence for the sensor: after all, the function of the adhesive is to hold the sensor on the skin! So it is particularly important to look at what can be done to improve adhesion. Three practices are often mentioned by allergy sufferers:

  • extensive use of adhesive barriers such as SkinTac at multiple parts of the cycle (to increase adhesive strength), but in particular on the skin and under/on the Dexcom adhesive pad itself. Drenching the adhesive pad itself, particularly when it has been trimmed, is often mentioned.

  • use of an additional adhesive layer on top of the sensor pad, extending out all the way to the skin outside the substrate.

  • hairdrying the sensor when it has been exposed to water, such as in showers or swimming. it is possible that sealing the full substrate with an adhesive like SkinTac once it is fully assembled may help keep the dissolving power of water at bay



Example: serious allergic reaction to adhesive

There probably are as many routines to deal with Dexcom allergies as there are allergy sufferers. The right routine to a specific allergic condition is often reached after many failed attempts. As an example, the following routine could be the routine of a specific PWD suffering from a significant Dexcom allergy (your own routine WILL be different):

  • thoroughly clean the site with alcohol to destroy germs and remove oils

  • immediately wash thoroughly with warm water and mild soap, to prep skin and decrease chance of alcohol reaction

  • dry thoroughly with air

  • spray a couple of squirts of Flonase over site area

  • lay out a large SkinTac layer; let dry till tacky to the touch; redo two more times

  • cut out a sensor opening in a Tegaderm dressing; apply to site; spend 30 seconds brushing fingers over Tegaderm to improve adhesion

  • apply one layer of SkinTac as previously

  • apply a hydrocolloid dressing to site, without a sensor opening; spend 30 seconds brushing fingers over Tegaderm to improve adhesion

  • apply one layer of SkinTac as previously

  • trim Dexcom sensor pad to minimal area, to decrease allergy potential.

  • soak sensor pad adhesive layer with SkinTac (using bottle applicator, not wipe).

  • apply sensor pad to site on top of hydrocolloid dressing; brush and tap sensor pad adhesive for one to two minutes with fingers to apply it securely; quickly apply Tacaway adhesive remover to fingers to get rid of SkinTac, then wash fingers in lukewarm water and soap to avoid reaction to alcohol

  • apply a wide layer of SkinTac as previously, on top of all adhesive layers and of the bordering skin

  • apply large Grif Grip dressing on top of Dexcom pad and surrounding skin to improve adhesion

When removing sensor:

  • apply Tacaway adhesive remover to area; wait 5 minutes

  • gently and slowly peel all layers at once

  • wash with lukewarm water and mild soap; dry well

  • apply calendula oil to remove adhesive residue

  • wash with lukewarm water and mild soap; dry well

  • apply antiallergenic moisturizer

When sensor has been soaked in water:

  • when possible, quickly dry with hairdryer



Sources and Resources

There are hundreds of threads discussing allergic reactions to Dexcom sensors on the DOC. I have found the following links to be particularly helpful:

Arden’s Day:

This is Caleb (Lorraine):

Inspired by Isabella:

Arceneaux Family:

Kerri Sparling at SixUntilMe:

Insulet product guide p.15:

tuDiabetes – Best method for removing Dexcom adhesives:

tuDiabetes – Omnipod Rash:

tuDiabetes – G4 adhesive issues:

Children with Diabetes – successful use of Dexcom w adhesive allergy:

End of wiki ---------- comments start here


Thank you for such a thorough wiki! What a great resource. :+1:

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Thank you! There is so much info, and so contradictory – I have been trying to write this for several months, but the sheer amount of research took me a long time.

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WOW! I counted 10 applications of Skin Tac in your instructions (including soaking the Dexcom pad). That’s a LOT of Skin Tac.

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Understand, this is just an example. Another person might have 0 - particularly if they are allergic to SkinTac…

[EDIT] OK @Dave, just for you I took a few of them off :slight_smile:


Thank you so much for doing all of this research! I can’t wait to read through it when I have a chance.

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