Moisture Is the Quiet Enemy of Pills and Capsules
Most supplements are physically easy to ship — sealed bottles of tablets and capsules are compact, unbreakable, and stable — which lulls sellers into treating them casually. The one threat that isn't obvious is humidity. Capsules are made of gelatin or cellulose that absorbs moisture and softens; tablets can swell, discolor, or begin to break down; and hygroscopic ingredients (many powders and some vitamins) pull water out of humid air and clump or degrade. This is why supplement bottles ship from the factory with a desiccant packet and a sealed induction liner — and why a bottle that's been opened, or one shipped through a humid summer in a permeable package, can arrive subtly compromised.
The defense is to preserve that factory seal and add a moisture barrier of your own when conditions warrant. Keep sealed bottles sealed; don't decant into baggies for shipping. Tape the caps so they don't loosen and break the seal in transit, and for humid routes or opened product, a poly bag around the bottle keeps ambient moisture out. Gummies are the special case — they're sugar and gelatin, they absorb humidity and melt in heat, and they'll fuse into a single mass in a hot, damp box — so treat gummy supplements more like a confection than a pill.
💡 Don't remove or defeat the factory seal and desiccant. That induction liner and little silica packet are the supplement's moisture protection — a decanted bottle or a broken seal is a bottle that can degrade in a humid box. Ship it as the manufacturer sealed it.
Labeling and Compliance: Selling Is Regulated Even If Shipping Isn't
Shipping supplements domestically is not itself restricted, but SELLING them is regulated, and the two get conflated. In the US, dietary supplements fall under DSHEA and FDA oversight: labels must carry a Supplement Facts panel, ingredient list, net quantity, and the manufacturer or distributor's identity, and the claims you can make are constrained — structure/function statements are allowed with the standard disclaimer, but disease claims ('cures,' 'treats') are not, and crossing that line turns a supplement into an unapproved drug in regulators' eyes. Sellers also need to mind lot numbers and expiration dating, which matter for recalls and for what a buyer is willing to accept.
For a small brand or reseller, the practical version is: ship product that is correctly and completely labeled, with a legible lot and expiry, and don't add marketing inserts that make disease claims the label can't. Amazon and other marketplaces layer their own supplement rules on top — expiration-date requirements, prohibited-ingredient lists, and documentation demands — and getting them wrong means suspended listings, not just unhappy buyers. The shipping is the easy part; the compliance around what's in the box and what's claimed on it is where supplement sellers actually get into trouble.
The Border Problem: US-Legal Doesn't Mean Legal There
International supplement shipping is where sellers get blindsided, because ingredients sold freely on any US shelf are controlled or banned in other countries. Melatonin is prescription-only or restricted across much of Europe and elsewhere; DHEA is a controlled substance in several countries; high-dose vitamins and minerals exceed legal limits in some jurisdictions; certain herbal and hormonal ingredients are outright prohibited; and stimulant and 'pro-hormone' products face the tightest scrutiny of all. A shipment that's perfectly legal to send is not necessarily legal to receive, and it's the destination country's rules that decide whether it clears customs.
So before shipping supplements across a border, check the destination country's rules for the specific ingredients — not just the product category — and expect that some products simply can't go. Customs seizure is the common outcome for restricted ingredients, and the buyer loses both the product and often the shipping. Declare contents honestly on customs forms (mislabeling to sneak a restricted ingredient through is fraud, not a workaround), and when in doubt, decline the international order rather than gamble a customer's money on a border you didn't research. Domestically these products are simple; internationally they're a compliance question every time.
Heat, the Nutraceutical Trade, and Selling Honestly
Heat is the summer complication. Most tablets and capsules tolerate it, but the sensitive subset is real: probiotics are live cultures that die in heat and sometimes need cool-chain handling, gummies and soft-gels melt and deform, and certain vitamins and oils degrade. For those, the meltable-goods discipline applies — ship early in the week and early in the day, insulate in genuine heat, and know which of your SKUs actually need it. The US supplement industry is heavily concentrated (Utah is a genuine nutraceutical capital), and the FBA-and-DTC fulfillment machine around it has these seasonal habits built in.
Selling honestly closes the loop. Supplement buyers increasingly read labels and check dates, so disclose the expiration clearly, describe whether a bottle is sealed or opened and how full, and don't resell anything past date or of questionable storage history — an expired or heat-abused supplement isn't just a bad product, it's a safety and trust problem. Keep it sealed, keep it dry, respect the border rules and the heat-sensitive subset, and label it completely. Do that and supplements are one of the more forgiving things to ship; skip the compliance and the moisture control and the forgiveness disappears.