Peel one on, wear it, carry on with your day. Transdermal delivery has worked this way for decades, and wellness patches are a newer application of the same idea, which makes molecular size worth understanding.
Transdermal delivery is a well-established technology, and many of the ingredients in a wellness patch, ours included, are small enough to be plausible candidates for skin delivery. Vitamin patches specifically have a much smaller clinical evidence base than established drug patches like nicotine or estrogen, so they shouldn't replace prescribed treatment for a diagnosed deficiency. For everyday wellness, the appeal is simpler: a wearable, pill-free routine that's easier for some people to keep up with than another capsule.
Why people choose a patch
The appeal isn't a claim of better absorption. It's the format itself: no capsule to swallow, no water needed, one wearable step folded into a routine you already have.
One patch, applied to clean, dry skin
Roughly 8 hours, through the day or overnight
No pill, no water, nothing to remember mid-day
Good Sleep, Energy, Focus or Hormonal Balance
How transdermal delivery works
Your outer skin layer, the stratum corneum, is a barrier built to keep things out, which is exactly why transdermal delivery is interesting: get the formulation right, and a small molecule can cross it anyway. Nicotine and estrogen patches have done this reliably for decades, which is how the field learned what makes a molecule a plausible candidate in the first place.
The 500 Dalton principle
500 Daltons
One of the first things worth checking in a transdermal formula
Smaller molecules generally have an easier route through the skin barrier. Formulation still matters, but molecular size gives a useful first look at which ingredients are more plausible candidates for transdermal delivery.
In 2000, two dermatologists at the University of Amsterdam set out the rule of thumb the field has used ever since: to cross the stratum corneum, a molecule generally needs to weigh less than about 500 Daltons. Their argument was elegant. Essentially every known contact allergen is under 500 Da. So is every topical drug in clinical use, and every molecule in every approved transdermal patch. It's a rule of thumb rather than a law, and formulation, patch design and microneedles all shift the picture, but it's a useful starting point, and it's checkable: molecular weights are public.
Established transdermal references
Smaller wellness ingredients
Larger molecule
Nicotine and estradiol, at 162 and 272 Da, are the molecules transdermal patches genuinely built their reputation on, and most B-vitamins sit comfortably in that same smaller range. Cyanocobalamin, vitamin B12, is the exception at 1,355 Da: considerably larger than the classic 500 Da rule of thumb, which makes formulation particularly relevant for it, and it's also the vitamin most often marketed on a patch, ours included. Being under 500 Da is a useful first filter; it isn't, by itself, proof that an ingredient is absorbed from a finished product.
What's inside Asuno's formulas
Every Asuno patch formula lists its per-patch amounts on the pouch, so you can see exactly what's included before choosing a routine.
Good Sleep pairs melatonin and L-theanine, both well within the smaller range above, with magnesium, valerian root and B6. Energy is built around a full B-complex, including B12, the one larger molecule discussed above, printed at 1,000 mcg per patch. Focus is built around a B-complex too, and its B-complex includes the same B12 as Energy's alongside the smaller B-vitamins, plus L-theanine, N-acetyl carnitine, lion's mane and red ginseng. Hormonal Balance pairs folate, B12 and D3 with calcium, phosphorus and selenium, plus plant botanicals (dong quai, black cohosh, licorice root) and curcumin, an ingredient set that isn't meaningfully compared on a single-molecule scale like this one.
Choose your routine
Good Sleep
Melatonin · L-theanine · magnesium · valerian · B6
For the evening wind-down routine
Energy
Full B-complex: B1, B2, B3, B5, B6, biotin, folate, B12
For the start of the day
Focus
B-complex · L-theanine · lion's mane · red ginseng
For work, study or concentrated time
Hormonal Balance
Folate · B12 · D3 · dong quai · black cohosh · licorice root
For a simple daily wellness routine
See the ingredient science ↑ for how the actives in each formula compare on molecular size.
What current research actually tested
The strongest human studies on vitamin patches haven't been run in ordinary wellness users. They involve bariatric-surgery patients using a patch in place of medically required supplementation, a more demanding and clinically different use case than adding a patch to an otherwise normal diet.
The most direct comparison, published in Obesity Surgery in 2019, followed 44 gastric bypass patients a year after surgery: the 17 using a transdermal multivitamin patch were substantially more likely to have at least one deficiency than the 27 taking oral supplements, and serum vitamin D, B1 and B12 were all measurably lower in the patch group. A smaller 2022 pilot, and a later case report, point the same direction. Case reports also reinforce that an OTC patch shouldn't replace medically prescribed supplementation after bariatric surgery.
What that means for everyday use
Every study above answers one specific, demanding question: can a patch replace medically necessary supplementation in a high-risk surgical population? None of them tell us how a patch performs for a healthy adult using it as part of an ordinary routine alongside a normal diet, because that trial hasn't been run yet at meaningful scale. Until it is, treat any strong claim in either direction, that patches definitely work or definitely don't, as going beyond what's currently published.
For everyday wellness use, that leaves patches exactly where the short answer put them: not a substitute for treating a diagnosed deficiency, but a reasonable, wearable way to get a formula's ingredients into your day without another capsule.
Transdermal delivery is an established technology, and molecular size gives a useful way to understand which ingredients are plausible candidates for skin delivery. Vitamin patches are a newer wellness application of that idea, not a replacement for medically prescribed deficiency treatment. For everyday use, the appeal is simple: a wearable, pill-free format with clearly listed ingredients, and formulas built around different routines.
Patches are especially appealing when the format itself feels like an upgrade: something wearable, easy to work into a morning or evening routine, and free from another capsule to swallow.
Peel, apply, and wear for roughly 8 hours. Every pouch lists the formula and per-patch amounts clearly, so you can pick the routine that fits you.
Questions about patches
Are vitamin patches an alternative to pills?
Do B12 patches work?
Why do people choose a vitamin patch?
Are vitamin patches safe?
How long should I wear one?
- Bos JD, Meinardi MM. The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Experimental Dermatology, June 2000.
- Saurabh S, Gao Y, Maduka S, et al. Is Transdermal Multivitamin Patch Effective in Gastric Bypass Patients? Obesity Surgery, December 2019.
- Grammatikopoulou MG, Gkiouras K, Dardiotis E, et al. Peeking into the future: Transdermal patches for the delivery of micronutrient supplements. Metabolism Open, 13 July 2021.
- Culpepper T, Lux T, Trivedi S, et al. Prevalence of Postoperative Micronutrient Deficiencies in Bariatric Surgery Patients Who Use Transdermal Patches for Supplementation: A Pilot Study. Cureus, 16 June 2022.
- Babu HM, Spiro AJ, Hoang TD, et al. Micronutrient Deficiency and Wernicke's Encephalopathy in the Setting of Over the Counter Transcutaneous Multivitamin Patch Use Following Bariatric Surgery. AACE Clinical Case Reports, 5 October 2024.
- Molecular weights from the PubChem Compound Database, NIH National Library of Medicine, accessed 10 August 2026.
- Asuno Good Sleep, Energy, Focus and Hormonal Balance Patches supplement facts panels, as packaged and sold.
This article is general information about published research. It isn't medical advice, and nothing here is a claim that any product treats, prevents or cures a condition. If you're pregnant, breastfeeding, taking medication or managing a health condition, check with your doctor before starting any supplement.
