Brać / Wziąć - to take

Boli mnie głowa, więc powinnam wziąć tabletkę - I have a headache, so I should take a tablet

Brać, imperfective form    /    Wziąć, perfective form

Wzięłem ♂ / Wzięłam ♀ już dziś tabletkę - I've already taken a tablet today.

The past perfective form seems more useful when taking tablets because it is such a quick activity, it is completed very quickly.  The present imperfective form could be used to say you take tablets for a condition.

Biorę tabletki na nadciśnienie - I take tablets for hypertension.

Brać / Wziąć have other meanings apart from taking medication, depending on context.

Such as taking with your hands (grabbing), taking advantage of something, to overcome an obstacle and to have sex.

Note that the perfective verb, zabrać, might look like it is the perfective form of brać and seems an easier option than wziąć, but it is the perfective form of zabierać and cannot be used in the context of taking medication.  It does mean to take, but in other ways.  See Zabrać