LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > Licking envelopes
Yes, it is safe. The gum on envelopes is made from food-grade starch, usually corn-based, and it is not toxic. Licking an envelope will not poison you. The real hazards are a paper cut on your tongue from the flap edge and the ordinary germs that live on handled paper.
The adhesive on a standard gummed envelope is a water-activated starch, most commonly dextrin from corn or potato. It is essentially the same family of ingredients as food thickeners. Old rumors about toxic envelope glue trace back to a misunderstanding: decades ago some adhesives used animal-based glues that smelled odd, and the stories stuck around long after the chemistry changed. There is no lead, no solvent, and nothing in the gum that can make you sick in the quantity on one flap.
The flap edge of an envelope is thin paper, and thin paper cuts. A paper cut on the tongue heals fast but hurts disproportionately, and it is the most common licking injury by far. The second risk is germs: envelopes pass through many hands and sorting machines before they reach you. Neither risk is serious, but both are avoidable.
A damp sponge or a wet paper towel gives you the same seal with no tongue contact, and it is what mailrooms use when they seal hundreds of envelopes. A quick swipe of a glue stick on the flap works just as well. Tape over the flap edge seals it and adds tamper evidence. Or skip the question entirely: peel-and-seal envelopes have a strip you pull off, no moisture needed, and they are now the default at most office-supply stores.
| Sealing method | How it works | Downsides |
|---|---|---|
| Licking | Saliva activates the gum | Paper-cut risk, germs, bad taste |
| Damp sponge | Water activates the gum | Needs a sponge nearby |
| Glue stick | Adds adhesive to the flap | Can lump up if over-applied |
| Peel-and-seal envelopes | Pull the strip, press the flap | Slightly more expensive per envelope |
| Tape | Seals over the flap edge | Looks less formal on business mail |
No. Sorting machines do not inspect how an envelope was sealed; they only care that it stays shut. A poorly sealed envelope that pops open in the machinery is a problem, because loose letters jam equipment and get separated from their envelopes. Whatever method you use, press the flap firmly and give the gum a few seconds to bond. In humid weather, gum reactivates: envelopes sealed days earlier can stick to each other in a stack, which is a good argument for tape or peel-and-seal on mail you store before sending.
Envelope gum is generally corn- or potato-based, but manufacturers do not guarantee it is gluten-free or allergen-free, and formulas vary by supplier. If you have a serious wheat or corn allergy, do not lick envelopes: use a sponge or glue stick instead. This is one of those cases where the risk is tiny but the workaround is trivial, so take the workaround.
Ready to mail it? Send your letter with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is printed and mailed.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com