TL;DR Summary: A small Australian company makes a B12-infused oil, like massage oil. Rub it into your skin and the B12 diffuses into your system. It's supposed to work better than other delivery mechanisms. They have animal tests showing as much as 80% absorption, and they're currently doing a clinical trial on humans. That's vastly higher than you're going to get from sublinguals, and the oils are supposed to deliver steadier B12 serum levels than injection. Their website (http://www.b12oils.com) is terrible, lacking even basic information. But they're extremely helpful and the product seems to work well. I've summarized most of the need-to-know info here. The oils come in little bottles that measure out a 0.25ml squirt. Each bottle has about 50-60 "squirt" doses. They recommend one squirt/day, but I'm finding 3 or even 4 is working much better for my specific SNPs. They have two main B12 products: Pure methyl B12, with 3mg/ml of B12, 0.75mg mB12 per dose. Adeno/methyl B12, with 7.5mg/ml of Adeno and 2.5mg/ml methyl. So that's about 1.875mg adB12 and 0.625mg mB12 per dose. They say that is the proportion normally found in the body ("although of course this would be in a person who methylates normally"), and people with CFS/ME get good results with it. With my SNPs I think I'm doing better with more methyl. They also have pure-adeno, hydroxyl, hydroxyl/methyl, and others. Pricing is $50/bottle, roughly $1/dose. Buy 3 bottles (any combination) and the price drops to $40. I've only been using it for about 10 days, but so far the results are much better than the 20mg Country Life mB12 + 4mg adB12 I was using before. I might need 2-3 doses per day for best results -- still testing. I also tried IM and SC injection and neither seemed to work as well for me as the CL, so this is by far the best thing I've found so far. =============================== Much more detail: In this thread @Lynn_M said she'd been using a transdermal oil product for over a year and was very pleased with the results. I ordered some to give it a try. As I said above their website is terrible, but their "support person" Greg (who I later realized is Dr. Gregory Russell-Jones, director of the company) is extraordinarily helpful. He says he's not an MD, "just" a PhD biochemist with 25 years of studying B12 metabolism, so he's very familiar with all the relevant SNPs and reactions. Greg helped me clarify my understanding of how B12 metabolism works. For the benefit of anyone else who might be interested, here's what I've learned and how it applies to the oil products: B12 is used constantly in nearly all systems of the body, but especially the brain and nervous system. Sublinguals and injections (and the oil) raise the B12 level in serum, but the B12 is not usable in this state. It must be picked up by a "transporter molecule," transcobolamin II (TCII), and delivered to where it is needed. The problems with sublinguals, and even injections to a lesser extent, are absorption and duration. Sublinguals typically have very poor absorption, especially if you dissolve them quickly. Greg says "very, very little" of the B12 from sublinguals reaches the brain. Sublinguals and IM injections spike the serum levels of B12 for a short time but don't maintain it. SC injections are better but still not ideal. The oil is supposed to deliver B12 slowly over the course of 8 hours or more. For my specific situation one 8-hour dose per day wasn't enough to keep my symptoms under control, but it does seem to work much better than sublinguals or injections. More frequent application worked much better. Greg used the analogy of the TCII being like a ferry boat that carries cars across a river. Say the ferry carries 10 cars. Sublinguals and injections tend to spike the levels, so there are 100 or 1000 cars waiting in line for a little while. But before the ferry can carry them away, the B12 levels drop. So most of the B12 is lost and wasted. It does no good to have 1000 cars there for a short time; you want at least 10 or 20 cars there ALL the time, 24x7, so you can always load up a ferry whenever one shows up. The oil is supposed to excel at that. BTW this is why you're not supposed to suck on sublinguals -- they dissolve too fast. Not only do you absorb less, but you spike the levels for a shorter window of time. You want to dribble B12 into your system as slowly and as consistently as possible, to load up as many TCII's as possible. I asked Greg if there was any way to increase the number of TCII's so we could speed up the B12 pipeline. He said "Choose different parents?" So we just have to make sure we make the best use of the TCII we have. The TCII ferries can deliver B12 to the brain or wherever it is needed at the moment. If there is no B12 in serum, the TCII can load up from the B12 reservoir in the liver. Ideally the liver holds about 5mg of B12 in reserve. (The brain may store a reserve too -- not sure on that point.) But if your B12 requirements are higher than your B12 supply -- which is typical for those of us with the various B12-related SNPs -- then the reservoir in the liver eventually gets drained. Then you have no source of B12, the TCII ferries are empty, and you start to show acute B12 deficiency symptoms, e.g. CFS/ME. (I suspect this is what happened to me over the past 1-2 years: with age my ability to process and deliver B12 decreased. I had periodic symptoms as my B12 supply fluctuated. I eventually drained my liver's B12 reservoir, and then I started feeling like crap.) One interesting side factoid was that MTFR/MTRR appear in the population at much less than expected Mendelian levels, because fewer fetuses with the mutations survive. In countries where they don't supplement with folate, the incidence of the MTFR/MTRR SNPs is only 3% or so. In countries where they do supplement, the levels of the SNPs are much higher. As are levels of autism &etc. The oil is supposed to keep your serum levels high at all times so the TCII is always loaded up for immediate needs, AND for re-stocking the reserves in the liver. Greg warned that it could take a year to fully top up the reservoir. He says many people get good results from a single dose per day. In 10 days of testing, I found it only seemed to work for 4-6 hours for me. In the last few days I've boosted to 3-4 doses/day, and my symptoms have mostly disappeared. My muscles are still a trifle achy/tingly but my energy level is better and I'm sleeping soundly through the night. (And this is in spite of "challenging" it for the last few days. In the last several months I haven't been tolerating alcohol at all well. The last 2 days I got together with friends and had 3-4 drinks -- and had no adverse effects!) This is MUCH better than I was doing with 20-30mg/day of CL mB12 plus 4mg/day of adB12. Greg says it sometimes takes a few weeks for people to "take to" the oils, and it takes about a full month to get full benefit, so in another week or two it may start working better and I may be able to back off to 1-2/day. After some period of using extra doses, I should fill up my reserve tank, and after that I think I can probably back off to a lower level. But the results I'm getting with ~3 doses/day are well worth it to me. I'll be happy to use the higher dosages for a year if it means my symptoms vanish and the re-supplied reservoir will once again protect me from deficiency. Using the oils: just squirt a dose into your hand and rub it into your skin. Leave it on, i.e. don't wash it off. Greg says you can rub it anywhere, but I suspect it might work better if applied to fatty tissue. So I've been applying it around my belly and midsection. The oil is quite red, but it rubs in fine. I might notice a very slight rosy glow where I've rubbed it in, but I might be imagining it. So that's what I know about the oils so far. I'm very pleased with the results I'm getting and I'm excited to see how it improves over time.