Can birth control be used if a person has essential thrombocytosis?

Yes!: With essential thrombocytosis, as well as any other condition that increases the likelihood of a blood clot, there is a concern that estrogen in a contraceptive methods will increase risk of clots even more. In these cases, methods without estrogen, like progesterone-only birth control pills ("the mini pill"), progesterone-releasing or copper iuds, depo-provera, and condoms are all good options.

Usually yes: Birth control- oral contraceptives (ocp) ? Condoms? Foam? Iud? Subq q shots? I assume ocp is your issue- answer is yes unless you have also had blood clots in veins. This is a good question to discuss with your oncologist or hematologist who should be seeing you on a regular basis.