https://www.amazon.com/NOW-Foods-PEPPERMINT-TWINPACK-SGELS/dp/B0015KYQEA/ref=mp_s_a_1_25?crid=1XLF2RGSQDKB5&dchild=1&keywords=peppermint+oil+now+foods&qid=1633281812&sprefix=peppermint+oil+now&sr=8-25

It's unavailable on Amazon but I found them in shops selling health supplements