Learn Spanish (Latin America): Voy a la farmacia a comprar la medicina. - I am going to the pharmacy to buy the medicine.

In Spanish, when you use a verb of motion like ir (to go), you connect it to the next action with the preposition a. Even though English speakers often want to use para to mean "in order to," after a motion verb you must use a. That's why it is Voy a la farmacia a comprar... (I am going to the pharmacy to buy...).

How would I change this sentence to say "I must go to the pharmacy" using deber?

To show personal obligation using the grammar from this lesson, swap voy (I am going) for debo ir (I must go). The rest of the sentence stays exactly the same: Debo ir a la farmacia a comprar la medicina.

Could voy a comprar just mean "I am going to buy" as a future plan?

Exactly! The formula ir + a + infinitive is the most common way to talk about future plans in Spanish. While this specific sentence highlights a physical trip because of a la farmacia, the phrase voy a comprar by itself naturally translates as "I am going to buy" meaning you plan to do it soon.

Is medicina the only word for medicine in Latin America?