Rash under Dexcom G6 sensor

After 12 continuous years of using Dexcom sensors, my last two have caused a rash underneath. It is persisting more than ten days after taking off the first one. Never had that problem before with Dexcom.

Anybody else experiencing this?

I put down a layer of Tegaderm before inserting the third one in the batch. Since Medicare is only allowing me three sensors at a time, I didn’t want to take the second one off even though it was itching and I knew would cause a rash.

I tried calling Dexcom for answers, but they won’t even talk to you if you have a Tandem pump, transferring you to Tandem. Tandem listened to my problem and transferred me back to Dexcom. Dexcom finally took the call and told me that they had “recently” made a change in the adhesive formula and now are receiving calls about rashes. But the info on their website does not mention that. It’s all about how to avoid skin irritation:

They were unable to identify G6 lot numbers. They do not intend to notify users of the adhesive change, the problem or any solution. So I will be using Tegaderm under every sensor from now on. They did replace two sensors for me. Just wish there were some way they could communicate problems to us.


I think they switched adhesives a while back, and the new ones are worse for those of us with sensitivities. I now don’t even try to restart sensors, because wearing them for more than a week causes issues, which was never a problem before (used to regularly wear them for at least 3 weeks at a time).


I have used Tegaderm for several years, nearly since I began with Dexcom. It works like a charm!


Found out how to apply the barrier film!

After zero help from a Dexcom support person tonight (transferred me to Tandem) I found the answer to how to apply the barrier film under a Dexcom patch: you punch a hole in the barrier film, then remove the sensor patch paper with the code number and apply the sensor patch to the back of the barrier. Then remove the paper protecting the barrier film’s sticky side and put it on and inject the wire. That way you can line up the holes exactly. A true genius posted a YouTube video of it back in 2018. https://youtu.be/Mtl6KN1PZtU

When I looked at my first sensor that failed after 3 days I found that by putting the barrier film (hydrocolloidal bandage) on my skin first I had missed the hole in the bandage and injected the sensor wire through the hydro gel beside it.

The YouTube video also recommends a barrier film that is just a one-layer tape, not the gel-filled hydrocolloidal bandage. Smith & Nephew 5466000040 Opsite Flexifix 2 Inch x 11 Yards Transparent Film Dressing. Available on Amazon https://www.amazon.com/gp/product/B0070P81CW/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

Tegaderm did not work for me, since it is not vapor-proof. After a few days the rash developed.

Dexcom is still just flailing around on this one. But a T1’s mom figured it out two years ago.

Later note: the Opsite Flexifix did not work for me as a barrier film, and the rash developed anyway. I am back to 3M hydrocolloidal bandages. The gel may ooze our and screw up the sensor, but at least I don’t get the intolerable itching and rash.


Yes, yes, yes! The last 2 sensors that I have restarted (so wore them for 20 days), I got a red bumpy itchy rash under the adhesive. I used OTC 1% cortisone cream and CeraVe cream, which solved the itchiness, but the bumps still haven’t gone away. I never had a reaction to the adhesive before.


Thanks for sharing this. I am having the worst time with reactions to the Libre sensor tape. I can’t wear sensors for the full two weeks due to extreme itchiness and rashes that take about two weeks and some steroid cream to heal. Unfortuantely, even when I apply a thick hydrocolloid barrier patch (the thin barrier films or sprays don’t work, I still react right through them) under the tape with a tiny 5 mm hole cut into it for the sensor wire, I still have enough of a reaction from the minute amount of adhesive touching my skin through the tiny hole that I still can’t wear the sensor for the full two weeks. It is beyond frustrating. My allergist thinks I’m allergic tto acrylates, which is a common ingredient in both sensor and infusion set tape (I also have problems with reactions to infusion sets, currently changing every 24 hours and still having reactions) as well as many other products. I may pay out of pocket to try the Dexcom G6, especially if I end up switching to the t:slim at some point, but @cardamom and others complaining about reactions with recent sensor tapes doesn’t give me much hope, and I’m nervous that if I am allergic to acrylates, the Dexcom tape also contains that ingredient. I do like the idea of being able to cut a hole and line it up exactly with the Dexcom sensor hole, though.


Hey @Jen … it’s so good to see you in print again. It seemed like it had been a very long while since you had been around, or it could have just been me, not seeing your posts!

As for testing out Dexcom G6 adhesive … why not give them a call and explain the situation. Ask if they can ship you just one of the sensors to “wear” to see if your skin reacts negatively to the adhesive. I’m thinking they would do that. It won’t be connected to a receiver, so it won’t be a workable model, but it will let you understand your options.

For what it’s worth, I’ve been ok lately going just 10 days with G6 sensors, and not trying to extend them further. I feel like since I’ve been keeping my skin from getting irritated, it’s been less sensitive moving forward too. However, it means I’m going through my sensor stash much much more quickly, and while that’s still annoyingly pricey with co-pays, I imagine it could be prohibitively so self-pay. The adhesive on the G6 does seem stronger to me than on the G5—I have to be careful not to damage my skin when removing it after just the 10 days, because it’s usually still stuck on pretty strongly, vs the G5s, which without additional tape would often have been close to falling off by then. So it may also be a different one than the G5. Even if so, I’m leaning away myself from pushing it with exposure time, since it seems like once my body decides something is worth reacting to, it’s much harder to get it to stop.

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@Jen, I am still getting an allergic reaction at about day 4 from the 6mm hole that my 1/4" leather punch makes in the hydrocolloidal bandage I am using for the barrier. I am considering just removing the Dexcom adhesive entirely before inserting and using Tegaderm over the top of the transmitter to hold the patch to my skin. Won’t work in summer, when sweat would be real problem, but might work for now. But the Dexcom patch has no plastic backing for the adhesive in the rear (rounded) part, and I am concerned about triggering the insert mechanism (it comes already cocked) while removing the adhesive. EDIT - I have now removed the adhesive from the next sensor I took off, and THE WIRE FELL OFF. So removing the adhesive is NOT the way to go with the G6.

I just hope Dexcom will eventually do something, and wish they had done some research before pushing out the adhesive change last December that was likely to cause problems for some of us. Also wish they would notify us of changes like that–my endo was surprised by it and said she had seen the same allergic problem “twice this week” so Dexcom did not put out any notice to doctors either.

@Tapestry had a good idea about asking Dexcom for a sample to test. If I succeed in removing an unused adhesive patch I will let you know. Don’t think you really want a used one to try. . . :slightly_smiling_face:


I haven’t used the g6 yet but even the g5 caused a lot of irritation and wouldn’t stay on for more than a few days without tegaderm under it. I won’t even bother trying the g6 without it…

I also punch right through it, works fine…

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Not your imagination…my posting on forums has gone way down in the past few months. :slight_smile:

This is a good idea, thanks! I may see if they’ll do this. In fact, when I first started on the Dexcom, I tried it out for a month before committing, precisely because I was concerned about reactions (given my history with infusion sets). But I may just buy the starter pack that comes with three sensors, becuase I can often tolerate something for a period of time before my immune system goes, Nope, don’t like that! and starts reacting.

That’s so great to hear. Unfortunately, for me the intense itching and soreness starts at about day three or four, and about day eight has been when I can no longer stand it (interrupted sleep, trying to scratch through the tape, worried my skin is disintegrating) and take the sensor off. So I am not at all sure I’d bea ble to even make it ten days if I end up reacting the same way to Dexcom.

I find the same thing. And I also find my level of reactivity is connected to my allergies overall. Sometimes my body gets into such a reactive state with allergies and eczema and all my old reaction sites flare up and start itching all at once and I just take a break from sensors and infusion sets and do shots for a week (and recently have begun having injection site reactions doing that, sigh). For me, it seems like my body starts reacting to anything it’s exposed to for long enough. So even if I’m fine with something at first, it’s likely (in my experience) that in a year or two I won’t be. This is where a lot of my frustration comes from. I have some fairly extensive allergy appointments coming up to get patch testing done, and am hoping that will help reveal exactly what I’m reacting to, although in the end it may not help if I can’t actually avoid the ingredients.

This is identical to my experience, both in timing of reaction (at about day four) and in reacting to even a minute millimetre of adhesive touching my skin at the edge of the hole I cut. I’m fairly sure this is pretty typical of an actual allergic reaction, as opposed to “just” irritation that many people get. The reactions I have (rash, itching, burning, soreness) also continues for a week to a month even after removing the sensor.

I’ve seriously considered doing this, too. I think it’s a little easier with the Libre. I would definitely be concerned about the Dexcom accidentally activating. I may give it a try and see if it helps. I am worried that I’d still react to any residue of the adhesive that may remain behind. But it’s worth a try.

Abbott’s response when I told them that I was having allergic reactions to the sensor adhesive was that I needed to stop using their product as the allergic reactions can get worse over time (hence they have definitely heard about them before!) and had to fill out a long series of questions because I said I needed to use medication to treat the reaction.

Since I’m dealing with a likely allergic reaction and not just irritation, the semi-permeable barriers like Tegaderm are basically useless when I’ve tried them, I just react right through them. Hopefully once I can figure out which ingredients my immune system is reacting to I can find products that don’t contain them. At the moment all the standard recommendations like Tegaderm, Opsite Flexifix, Skin Tac, Cavilon spray and so on all contain acrylics/acrylates or colophony, all of which are common allergens and I seem to react to. So once I have confirmation of what exactly my immune system hates, hopefully I can do some research and find a barrier that does not have eny of those ingredients.

Every time I’ve tried punching straight through the barriers the sensor fails. Maybe because I’m having to use thicker barriers such as hydrocolloid bandages. I can’t remember if I tried it with the thinner barriers, it’s possible it worked there. But the YouTube video linked above also mentions the problem of injecting directly through barriers is that a minute amount of the adhesive ends up being “injected” into the skin as the insertion needle passes through it, which creates reactions for those dealing with actual allergies. Though probably not a problem if all you have is sensitive skin. Maybe that’s why I still reacted even when using the thinner barriers or the barrier sprays.

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I understand that thought process but it just doesn’t strike me as a reflection of reality with tegaderm after having experimented and having done it on myself a lot… it’s a super sharp needle puncturing through a piece of film that’s stretched over a surface… I just don’t imagine it’s taking anything with it

It’s pretty much scientifically proven that contact with minute amounts of allergens, invisible to the naked eye, can be detected by the immune system and trigger an allergic reaction, though… So I don’t think expereince with skin irritaiton is comparable to an actual allergy. If I try this technique, it would be with a hydrocolloid bandage, which is the only barrier I’ve found to work (as it’s impermeable), aside from the fact that I still seriously react to the minute amount of adhesive touching my skin through the hole. The hydrocolloid bandages are significantly thicker than other types of films and tapes, though, so sensors cannot be inserted direclty through them, at least not with the Libre (I’ve tried).


For what it’s worth, I buy it, since mine isn’t exactly an allergy, but likely a mast cell reaction (so similar, if less severe at least so far), and I’ve found that the spot with the actual Dexcom wire gets particularly itchy and irritated too when my skin does.

Also @Jen, with the G5 I was having itchiness/irritation much sooner, within a few days, though tolerable enough to keep going for the week. The G6 seems to be bothering me somewhat less for some reason, though occasionally itchy still. I do think the two use somewhat different adhesives, since the G6’s is much more effective.

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Yeah, a mast cell disorder is definitely on my allergist’s radar as a possibility for me, too, though so far the one blood test I did was normal. I’ve found myself wondering if I’m reacting to the sensor wire, especially given my issues with reactions to the cannula/needle of infusion sets. But, so far, it seems to be primarily an issue with the adhesive for the sensors, and I’m now reacting to both the cannula/needle and adhesive on infusion sets. (I’m very lucky that I’m able to change infusion sets daily…there is no way I’d be able to use one for three days; even after 24 hours, there’s usually a reaction.)

As best I understand it, blood tests for MCAS are rarely conclusive. 24 hour urine capture tests sometimes are, but still miss at least half the real cases. Most people seem to get a clinical diagnosis made by exclusion (negative allergy tests for things people have clear reactions to), presence of reactions that are pretty specific to MCAS (like reactivity to temperature change, “allergy” to sun, skin puffiness when scratched), and responsiveness to treatment. I have the latter two—was in process of ruling out real allergies when COVID hit, so that got delayed for the time being (but seems unlikely anyway to me).

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Interesting, I didn’t know lack of positive allergy tests was a consideration. I have had many positive allergy tests to things I react to, but I’ve also had unexplained severe reactions a handful of times, which is why my allergist was thinking of a mast cell disorder. I also used to be severely allergic to the cold (cold urticaria), but thankfully outgrew that, which seems pretty typical. I also have idiopathic urticaria as well, but my allergist describes that as more of an autoimmune issue. So it seems maybe I just have a ton of actual allergies. We’ll see if this upcoming testing helps determine what I’m reacting to in the adhesives.

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I think you can have both allergies and MCAS, so positive allergies to some things doesn’t rule it out, so much as if you have a bunch of reactions but no positive tests, might be MCAS. Like I definitely react to a number of high histamine things (e.g. walnuts, fish sauce, strawberries), but never anaphylaxis and doesn’t seem to be on a contamination level, so my hypothesis is that my allergy tests will come out negative to those. Plus, for me, they all came on pretty much together as my symptoms got worse in past few years—I used to be able to eat all of those things fine, except for occasionally having what I know in retrospect realize were reactions to extremely rich meals with lots of reduction sauces and wine and otherwise loaded with histamines (but I did that very rarely, so never bothered thinking about it much).

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@Jen, I have found online a good number of people who used the Dexcom G5 with hydrocolloid bandages, not sure about the G6.

Do you mean people who are able to insert the sensor wire directly through the bandages without having to punch a hole? It could be that it would work with the Dexcom but not the Libre, for whatever reason (maybe angled versus straight-in insertion makes a difference?).

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