The one major difference that separates iodine is whether it is a certified supplement or just “home brewed”. Certified supplements are bottled in facilities that have routine inspection and cleaning etc. Home brewed could be using the same exact raw materials, but they are mixing and bottling in unknown conditions. Some of these home brewers have make-shift labs that are just as clean as the supplement facilities, others rinse pet fur out of their equipment as they randomly create a batch.
J. Crow, a commonly purchased brand of iodine is sold by several different suppliers on Amazon. But even when purchasing directly from their website, people have reported receiving very old product with dry-rotted droppers or what seems like watered down product. They also sell iodine in several gallon plastic containers which causes me to think they create large batches of iodine at once and allow it to sit on the shelf for an unknown amount of time before bottling and shipping. Apparently, they may replace droppers if you contact them.
Some brands use a “Shipping Cap” for shipping and storage, and provide the dropper in a separate bag. This means the iodine and the rubber have not been interacting since the solution was bottled.
Some brands use higher quality rubber droppers that do not degrade when coming in contact with iodine.
I buy iodine in a bulk 32oz quart bottle and refill small 1 ounce bottles. This is much more economical, the shipping cap keeps the bulk iodine fresh and the droppers of my 1oz bottles do not come in direct contact with iodine unless I knock it over, which is still different than shipping or storage.
By keeping my bulk iodine out of sunlight, heat and sealing with a better cap, it should last pretty much indefinitely. And by only having 1oz in a bottle with a rubber dropper that’s opened almost daily, I know my iodine is pretty fresh. Otherwise, by the time I’m finishing my bottle, it could have been stored for a handful of years and the rubber dropper could barely be making a seal anymore.
Common brands in the community
Some info about brands you may commonly see recommended across the various groups.
"Talisman Only" Iodine
Zen Haus and Miss Lizzy’s products are supplements which means there is a good chance they will be produced to a higher standard.
Most of these other brands of Lugols liquid below state that they are Talisman Only, which is their way of attempting to avoid liability if someone were to become injured by consuming this. Without extra regulations that supplements go through, the quality of these products is unknown without testing each one on our own.