Doktorica kaže da mučnina nije uvijek ozbiljan simptom, ali da treba piti dovoljno vode.

Doktorica is the feminine form of doktor and means female doctor.

• doktor = doctor, male doctor, or sometimes doctor in a general sense
• doktorica = female doctor

Since the sentence is about a woman speaking, Croatian uses doktorica.

Kaže means says.

It is the 3rd person singular present form of the verb kazati or reći in the sense of reporting speech.

So:

• ja kažem = I say
• ti kažeš = you say
• on/ona kaže = he/she says

Here, Doktorica kaže... = The doctor says...

In Croatian, da is very commonly used to introduce a clause after verbs like say, think, know, see, etc.

So:

• Kaže da... = She says that...

English often allows you to omit that:

• The doctor says nausea is not always a serious symptom

Croatian normally keeps da in this structure:

• Doktorica kaže da mučnina nije...

The sentence has two reported statements joined by ali (but):

1. da mučnina nije uvijek ozbiljan simptom
2. da treba piti dovoljno vode

Croatian often repeats da when two subordinate clauses are coordinated. This makes the structure clearer and sounds natural.

So the pattern is:

• kaže da X, ali da Y

In English, we might say:

• The doctor says that X, but that Y or simply
• The doctor says X, but Y

Croatian prefers the repeated da here.

Nije is the negative form of je (is).

So:

• je = is
• nije = is not

This is normal with forms of biti (to be):

• nije = is not
• nisam = I am not
• nisu = are not

So:

• mučnina nije... = nausea is not...

Mučnina is in the nominative singular.

It is the subject of the clause:

• mučnina nije uvijek ozbiljan simptom
• nausea is not always a serious symptom

Since mučnina is the thing being talked about, it appears in the nominative.

Ozbiljan simptom means a serious symptom.

Both words are in the nominative singular masculine:

• ozbiljan = serious
• simptom = symptom

This happens because after biti (to be), Croatian often uses the predicate noun/adjective in the nominative:

• To je problem. = That is a problem.
• On je liječnik. = He is a doctor.
• Mučnina nije ozbiljan simptom. = Nausea is not a serious symptom.

Also, Croatian has no articles, so ozbiljan simptom can mean a serious symptom or sometimes the serious symptom, depending on context. Here it means a serious symptom.

Uvijek means always, and in Croatian adverbs like this can move around more freely than in English.

Here:

• nije uvijek ozbiljan simptom = is not always a serious symptom

This word order is very natural. It emphasizes that nausea is not always serious.

You may also see slightly different placements in Croatian, but this version is standard and idiomatic.

Treba piti means one should drink, you should drink, or it is necessary to drink, depending on context.

Here, treba is being used impersonally. There is no stated subject like ja, ti, or on.

So:

• treba piti = it is necessary to drink / one should drink

In this sentence, the natural English meaning is:

• ...but that you should drink enough water or
• ...but that it is important to drink enough water

Because Croatian often uses impersonal constructions where English would use you, one, or a general statement.

So instead of saying:

• you should drink enough water

Croatian can simply say:

• treba piti dovoljno vode

This is very common and sounds natural, especially in advice, instructions, and general truths.

Piti is the infinitive of the verb to drink.

After treba, Croatian commonly uses an infinitive:

• treba piti = should drink / it is necessary to drink
• treba ići = should go
• treba učiti = should study

So treba + infinitive is a very useful pattern.

This is a very common learner question.

After quantity words or adverbs like dovoljno (enough), Croatian usually uses the genitive.

So:

• dovoljno vode = enough water

Here:

• voda is the dictionary form, nominative singular
• vode is the genitive singular

Compare:

• Pijem vodu. = I am drinking water.
  (vodu = direct object, accusative)
• Pijem dovoljno vode. = I am drinking enough water.
  (vode after a quantity expression)

This is similar to how Croatian handles many quantity expressions.

Not perfectly. The structure is similar, but some parts work differently.

A close breakdown is:

• Doktorica = female doctor
• kaže = says
• da = that
• mučnina = nausea
• nije uvijek = is not always
• ozbiljan simptom = a serious symptom
• ali = but
• da = that
• treba piti = one should drink / it is necessary to drink
• dovoljno vode = enough water

A natural English translation would be:

• The doctor says that nausea is not always a serious symptom, but that you should drink enough water.

So the meaning matches well, but English and Croatian organize some ideas differently, especially with da and treba piti.

Yes, it sounds natural and standard.

It has a slightly informative or medical tone because of words like:

• mučnina = nausea
• ozbiljan simptom = serious symptom

But the grammar itself is very normal everyday Croatian. A doctor, article, or health leaflet could easily use this sentence.