Taiwan Foreign Ministry spokesperson Joanne Ou said that upon hearing the king was infected, Tsai arranged medical assistance for him.
“The Ministry of Foreign Affairs is gratified to hear of the eSwatini king's successful recovery under the joint care of Taiwanese and eSwatini medical staff,” she said.
The king could have been referring to Gilead Sciences Inc's antiviral drug remdesivir, which was conditionally approved in Europe in July for treating Covid-19 in adults and adolescents with pneumonia requiring oxygen support.
Taiwan also provisionally approved its use last year.
Using the slogan “Taiwan can help,” the government has been keen to showcase its assistance to other countries during the pandemic, donating face masks and other supplies.
China claims Taiwan as its own territory with no right to state-to-state ties. Only 14 countries now officially recognise the island's government.
eSwatini has recorded almost 17,000 infections of the coronavirus and 644 Covid-19 deaths.
Prime Minister Ambrose Dlamini died in a South African hospital in December after testing positive for Covid-19.