A 14 day course of metformin reduces long covid likelihood by 63% when started by day 3 of symptoms.
Summary:
https://www.cidrap.u...vent-long-covid
The paper (vs Ivermectin and fluvoxamine):
https://www.thelance...0299-2/fulltext
The dosage:
All study drugs were oral medications in tablet form. The metformin dose was titrated over 6 days: 500 mg on day 1, 500 mg twice daily on days 2–5, then 500 mg in the morning and 1000 mg in the evening up to day 14.