Taking ashwagandha with thyroid medication is not recommended but only do so under a doctors advise.
The ashwagandha taken with thyroid medication could cause some bad interactions so use caution if you do take it with the thyroid medication.
Women who are pregnant should not take ashwagandha because it could lead to a miscarriage.
Also if you're taking sedatives or antidepressants you should speak with your doctor to avoid any problems.
Ashwagandha is also best taken before bed for the best optimal thyroid health.