Are monthly insurance premiums considered a medical expense?

Yes if you have enough total deductions to itemize.  And you should enter all your deductions in case you can Itemize on your state return.

You can only deduct the amount of unreimbursed Medical Expenses you actually paid over 7.5% of your AGI.  And then all your itemized deductions have to be more than the standard deduction to get any benefit (so you would only be getting the benefit of the amount that puts you over the standard deduction).  And since the Standard Deduction is increased more people will not need to Itemize.

For 2020 the standard deduction amounts are:

Single 12,400 + 1,650 for 65 and over or blind (14,050)

HOH 18,650 + 1,650 for 65 and over or blind

Joint 24,800 + 1,300 for each 65 and over or blind

Married filing Separate 12,400 + 1,300 for 65 and over or blind

Yes you can enter the healthcare premiums you pay as a medical expense.  It is pretty hard to reach the threshold to get any deduction for medical expenses---and you also have to be able to use itemized deductions.

MEDICAL EXPENSES

The medical expense deduction has to meet a rather large threshold before it can affect your return. The amount of medical (including dental, vision, etc.)  expenses that will count toward itemization is the amount that is OVER 7.5% of your adjusted gross income. You should only enter the amount that you paid in 2020—do not include any amounts that were covered by insurance or that are still outstanding.  Of course, your medical expenses plus your other itemized deductions still have to exceed your standard deduction before you will see a difference in your tax due or refund.

To enter your medical expenses go to Federal>Deductions and Credits>Medical>Medical Expense