Blisters between the toes
Blisters between the toes (interdigital blisters) can be the most painful blisters of all. There are two types of blisters that could be classed as interdigital blisters:
- True interdigital blisters – blisters literally between two toes. These aren't as common as the next type - pinch blisters.
- Pinch blisters – blisters towards the bottom or end of the toe, common with adductovarus (curly) toes. The underside of the toe often takes on a triangular shape. These blisters are a result of how one toe curls under the next toe and basically gets 'trodden on' with a blister being the result.
The bony anatomy of the toes
Phalanges - toe bone anatomy
Toes are bony little things. There are 3 phalanges (toe bones) in each toe (except the big toe which has 2, like your thumb). Phalanges aren't smooth straight bones, they're pretty lumpy. Look at the x-ray of the big toe and second toe. In this image you can see the soft tissue of each toe and even the nails if you look closely. And you can see the phalanges under the skin. Notice how they are wide at the ends and skinny in the middle.
Even at the best of times, you can see how the bony prominence of one toe can press on the bony prominence of the adjacent toe. This is even more-so when a toe is bent or curly - one gets "trodden on" and pinched. And the toes don't necessarily remain still in the shoe as you walk and run. They move relative to one another.
Before we delve into ways you can prevent both types of blisters between the toes, have a look at the interdigital blister below.
How To Stop Blisters Between Toes
1. Foam or gel wedges
Foam and gel (pictured) wedges keep the toes physically separated and cushion bony prominences. The silicone gel material absorbs a lot (repeat, a lot) of shear via its very low shear modulus. Interdigital wedges are almost always comfortable because the material is soft. But they can dislodge and move around, because apart from the toes sitting close together, there's nothing actually holding them in place. In-shoe conditions (sweat/grit) cause them to degrade prematurely, especially foam wedges. These products are available at pharmacies and from some podiatrists.
2. Silicone gel toe sleeve
These are like a little sock for an individual toe and come either open or closed at one end. The best ones have gel all around thereby providing 360 degree toe protection. Compared to the wedges (above), they are more likely to stay in place because they are elasticised. The silicone gel material is the same so they still absorb a lot of blister-causing shear (in fact, silicone gel absorbs too much shear for the main weightbearing parts of the foot, but for toes they are perfect). They can be helpful for pinch blisters as they encapsulate and hold the soft tissue component of the toe together so it’s not getting "trodden on" as much with each step. Some people find they make the skin too sweaty; and I have seen this happen (a runner whose skin became macerated after 6 hours of wear). But I have also seen an ultramarathoner wear one of these 24/7 for 6 days (6-day ultramarathon) without skin maceration. So the relative success will be very subject specific, but I highly recommend trying them.
3. Otoform K wedge
Otoform K is a moldable putty material that sets and holds its shape. Podiatrists use it frequently to achieve an even pressure along the entire interdigital space, in spite of even the most significant toe deformities. It's the best way to achieve even pressure - better than cushioning methods (above). The aim is either to get the toe to sit straighter; or if not, at least prevent high focal pressure by moulding the material to the intredigital space. You need to be standing while the material sets - because nonwieghtbearing toe alignment is always different to weightbearing alignment. The good thing about Otoform K is it's long-lasting (months to years) and is easy to keep clean. However, they aren’t always tolerated because they can feel hard and foreign. Watch this video to see this material in action.
Tapes or dressings can be used to reposition a toe, to encapsulate the soft tissue of the toe or just to protect the skin from rubbing. To reposition a toe eg: a curly toe that tucks in & under the next toe, you can tape it up & out so that it sits a bit straighter. But tape stretches and/or comes loose over time so it requires reapplication each day or sometimes several times a day depending on your activity. Because sweat is a constant threat to adhesion. For toes that suffer pinch blisters, often the fleshy underside of the toe is misshapen to the point where it can be triangular! Anything that can hold this soft tissue in and less triangular, means there’s less toe that the next toe can tread on – and that means less blisters. Here's a video on toe taping technique by Anna Beetham that may help. There are a plethora of different tapes: Fixomul, Leukoplast, Rocktape, Kinesiotex ...). Read this for tips and insights about blister taping.
Lubricants reduce friction. However, research shows that there is a delayed increase in friction above baseline measures So reapplication is required or not only is your blister protection gone, you're actually more likely to get blisters. And lubricants are occlusive and lock sweat within the skin and increase maceration, a common issue between the toes anyway. On the upside, if used only between the toes, at least the initial lack of traction will be a minor issue at this anatomical location. Read this article for more on how lubricants work.
Toe-socks add a little more bulk to the interdigital space so they work a bit like an interdigital wedge by cushioning. They also work like a double-sock system by forming an additional interface (sock-sock) at the interdigital space. But double-socks rely on different materials being used for friction-reducing properties and this is not the case with toesocks – it’s the same material on each side. But this small difference may be enough to stop blisters. A common brand of toe-socks is Injinji. While toesocks can reduce interdigital blisters, it's not difficult to understand how they can cause the shoe to get too tight in the toebox and cause additional pressure and more blisters to the outside of the big and little toe.
7. Low friction tape on toesocks
Applying an ENGO Patch to toesocks will reduce friction a lot more than the toesocks alone. You'll only need it on one interdigital surface. Remember that foot volume increases the more you are on your feet and active - so don't apply any compression around the toe! Just lay it on and press to adhere. I know of athletes that use duct tape for this application, which may suffice considering any tape will come off when you wash the sock.