Sau khi ăn xong bữa tối, tôi sẽ uống thuốc.

Sau khi means after. It introduces an earlier action that must happen before the main action.

In this sentence:

• Sau khi ăn xong bữa tối = after finishing dinner
• tôi sẽ uống thuốc = I will take medicine

A very common pattern is:

• Sau khi + action, main action

So sau khi is functioning like after in English.

Xong means finished or completed. After a verb, it shows that the action has been completed.

So:

• ăn = eat
• ăn xong = finish eating

This is a very common Vietnamese pattern:

• làm xong = finish doing
• đọc xong = finish reading
• viết xong = finish writing

In ăn xong bữa tối, xong comes after the verb ăn to show the dinner is fully finished.

Yes, a little—but it is still natural.

Why it feels slightly repetitive:

• sau khi already means after
• xong already suggests the action is completed

So both together emphasize that the medicine is taken only once dinner is finished.

Shorter versions that are also natural:

• Sau khi ăn tối, tôi sẽ uống thuốc.
• Ăn tối xong, tôi sẽ uống thuốc.

So the original sentence is fine; it is just a bit more explicit.

Bữa tối means the evening meal / dinner.

So:

• ăn bữa tối = eat dinner
• ăn tối = have dinner

In everyday Vietnamese, ăn tối is often more common and more compact.

So these are all possible:

• Sau khi ăn xong bữa tối, tôi sẽ uống thuốc.
• Sau khi ăn tối, tôi sẽ uống thuốc.
• Ăn tối xong, tôi sẽ uống thuốc.

The version with bữa tối sounds a little fuller and more explicit.

Because the subject is already clear.

In Vietnamese, if the subject of both parts is the same, it is very common to omit it in the first clause or subordinate clause.

So:

• Sau khi ăn xong bữa tối, tôi sẽ uống thuốc.
• Sau khi tôi ăn xong bữa tối, tôi sẽ uống thuốc.

Both are grammatical, but the first one sounds more natural because it avoids repetition.

If the subject were different, you would usually include it:

• Sau khi mẹ ăn xong bữa tối, tôi sẽ uống thuốc.

Sẽ marks the future, similar to will in English.

So:

• tôi sẽ uống thuốc = I will take medicine

You can sometimes leave sẽ out if the future meaning is already obvious from context. Vietnamese often relies on context more than English does.

For example:

• Sau khi ăn tối xong, tôi uống thuốc.

This could still be understood as a future plan, especially in conversation.

But sẽ makes the future meaning clearer and more explicit, so it is a good choice here.

This is an idiomatic expression.

• uống literally means drink
• thuốc means medicine

But in Vietnamese, uống thuốc is the normal way to say take medicine, especially when the medicine is swallowed, including pills.

So even if English says take medicine, Vietnamese often says drink medicine.

A few related expressions:

• uống thuốc = take medicine
• dùng thuốc = use/take medicine, more formal or general
• bôi thuốc = apply medicine
• tiêm thuốc = inject medicine

It can mean either, depending on context.

Vietnamese does not use articles like a or the in the same way English does. So thuốc can mean:

• medicine in general
• the medicine already known from context

If you want to be more specific, you can add more words:

• thuốc này = this medicine
• viên thuốc = a pill / tablet
• thuốc bổ = vitamins / tonic medicine
• thuốc kháng sinh = antibiotics

In your sentence, thuốc most naturally means the medicine I am supposed to take.

Yes. That is completely natural.

Both are correct:

• Sau khi ăn xong bữa tối, tôi sẽ uống thuốc.
• Tôi sẽ uống thuốc sau khi ăn xong bữa tối.

The difference is mainly focus:

• Starting with Sau khi... emphasizes the time sequence
• Starting with Tôi sẽ uống thuốc... emphasizes the main action first

Vietnamese allows both word orders.

The comma separates the introductory time clause from the main clause.

So:

• Sau khi ăn xong bữa tối, = introductory time phrase
• tôi sẽ uống thuốc. = main clause

This is similar to English writing:

• After finishing dinner, I will take medicine.

In casual writing, people sometimes omit commas, but using one here is clear and standard.

Yes, it is natural and correct.

That said, many speakers might choose a slightly shorter everyday version, such as:

• Sau khi ăn tối, tôi sẽ uống thuốc.
• Ăn tối xong, tôi sẽ uống thuốc.
• Tôi sẽ uống thuốc sau khi ăn tối.

The original sentence sounds a little more careful or explicit because it includes both sau khi and xong, and it uses bữa tối instead of the shorter ăn tối. All of these versions are good; the best choice depends on how formal or conversational you want to sound.