A no-prescription offer is not an approval date
A page that offers the tablet without a prescription, or that calls it over the counter, is an advertisement. It is not an FDA approval date. Dates on this note come from the American Chemical Society landmark and the label.
The path is a soil screen, a chemical edit, a veterinary launch, then a human tablet and a donation.
Kawana soil and the chemical edit
Satoshi Ōmura, at the Kitasato Institute, collected soil bacteria and sent promising cultures to Merck. The Nobel account says he isolated new strains of Streptomyces from soil samples in Japan, and that one of those cultures later turned out to be Streptomyces avermitilis, the source of avermectin. William C. Campbell's group purified that product and chemically modified it to a more effective compound called ivermectin. The press release lists two 1979 papers in Antimicrobial Agents and Chemotherapy, Burg and colleagues and Egerton and colleagues, as the key publications.
The ACS landmark is more specific about the place, and it uses a different species name. It says the culture that cleared worms from mice was derived from soil collected near a golf course in Kawana, about 80 miles southwest of Tokyo. It says Ōmura identified that bacterium as a new strain, which was ultimately christened Streptomyces avermectinius. The Nobel press release and the current Stromectol label both say Streptomyces avermitilis. This note keeps both names side by side. It does not pick a winner between a chemistry landmark and a drug label.
ACS also says the ivermectin mixture was 25 times more potent than existing treatments for parasitic worms. That line belongs to the animal screen Merck was running. It is not a claim that every human infection shrinks by that factor. The label's own description is quieter: ivermectin is derived from the avermectins isolated from the fermentation products of Streptomyces avermitilis, and Stromectol is a semisynthetic anthelmintic for oral administration.
1981 for animals, 1987 for people
The same ACS account splits the clocks. Merck commercialized ivermectin as a veterinary treatment beginning in 1981. Starting in 1987, the drug was also marketed to the public under the brand name Heartgard to prevent heartworms in dogs. Heartgard is that dog product. It is not the human tablet labeled Stromectol.
Human use, in that account, was approved in 1987 under the name Mectizan, after a river-blindness trial in Senegal in 1981 directed by Mohammed Aziz. The same year, Merck CEO P. Roy Vagelos announced the company would donate as much as needed, for as long as needed, to help eliminate river blindness. ACS says the Mectizan Donation Program reaches more than 250 million people, with more than 2 billion treatments donated since it was established. Those are the landmark's figures for the program. They are not a tally this desk counted in October 2026.
Mectizan is the name on that 1987 human approval. Stromectol is the name on the US tablet label this site's dosing note counts. The weight tables belong there. This page only needs the identity: the history ends at a 3 mg human tablet, not at a dog chew.
The 2015 prize and today's 3 mg carton
On 5 October 2015 the Nobel Assembly awarded one half of the prize in physiology or medicine jointly to William C. Campbell and Satoshi Ōmura for their discoveries concerning a novel therapy against infections caused by roundworm parasites. The other half went to Tu Youyou for a malaria therapy. The press release says ivermectin killed parasite larvae, the microfilariae. It does not say the adult Onchocerca worm dies. That limit stays on the evidence note and on the medicine page.
ACS designated the discovery a National Historic Chemical Landmark at Merck in Rahway, New Jersey, on 2 December 2016. The plaque date is a commemoration. It is not a second approval.
What a US reader can hold is still the carton. Stromectol 3 mg tablets are white, round, flat, and bevel-edged, coded MSD on one side and 32 on the other. Each tablet contains 3 mg of ivermectin. The FDA has not authorized or approved ivermectin for use in preventing or treating COVID-19 in humans or animals. That sentence fences the history. It does not add a chapter to it.