Se eu continuar febril, vou à clínica amanhã.

Because after se when you are talking about a possible future situation, Portuguese normally uses the future subjunctive.

So:

• Se eu continuar febril... = if I continue to be feverish...
• not se eu continuo for this meaning
• not se eu continuarei, because Portuguese does not normally use the future tense after se in this kind of sentence

A very common pattern is:

• Se + future subjunctive, main clause in present/future

Examples:

• Se eu tiver tempo, vou contigo.
• Se chover, fico em casa.
• Se ela chegar cedo, jantamos juntos.

In this sentence, continuar looks exactly like the infinitive, but here it is actually the future subjunctive form for eu.

That is normal for many verbs in the future subjunctive.

For the verb continuar:

• infinitive: continuar
• future subjunctive:
  • se eu continuar
  • se tu continuares
  • se ele/ela continuar
  • se nós continuarmos
  • se vós continuardes
  • se eles/elas continuarem

So the eu and ele/ela forms are often identical to the infinitive.

This can be confusing at first, but after se, in a future condition, learners should expect the future subjunctive.

Febril is an adjective meaning feverish or having a fever.

So continuar febril means to remain feverish.

It is correct and natural, but it sounds a bit more medical or formal than everyday speech. In everyday conversation, many people would also say:

• Se eu continuar com febre, vou à clínica amanhã.

That version is often more common in casual speech.

So:

• febril = perfectly correct, slightly more clinical/formal
• com febre = very common, everyday way to say it

Because à is the contraction of:

• a = the preposition required by ir in this meaning
• a = the feminine singular definite article the

So:

• ir a
• a clínica
• together: ir à clínica

This is the same kind of contraction you see in:

• Vou à escola.
• Vamos à praia.
• Ela foi à farmácia.

If the noun were masculine, you would usually get ao:

• Vou ao hospital.

In Portuguese, the present tense is very often used to talk about the near future, especially when there is already a time expression like amanhã.

So:

• Vou à clínica amanhã.
• Irei à clínica amanhã.

Both are correct, but they do not feel exactly the same.

Generally:

• vou à clínica amanhã sounds more natural and conversational
• irei à clínica amanhã sounds more formal, more deliberate, or more written

This is similar to English using I’m going tomorrow instead of I will go tomorrow.

Also, because the main verb is ir, Portuguese often just uses the simple present rather than something like vou ir, which many speakers avoid.

You might hear it in some varieties or informal speech, but in European Portuguese it is usually better to avoid it.

Since the main verb is already ir, Portuguese normally prefers:

• Vou à clínica amanhã.
• Irei à clínica amanhã.

Using vou ir can sound repetitive because it is basically I am going to go.

So for a learner, the safest and most natural choice here is:

• vou à clínica amanhã

Because Se eu continuar febril is a conditional clause placed before the main clause.

In writing, Portuguese normally uses a comma after this kind of introductory clause:

• Se eu continuar febril, vou à clínica amanhã.

If you reverse the order, the comma is often not needed:

• Vou à clínica amanhã se eu continuar febril.

So the comma here is standard punctuation.

No, not always.

Portuguese often drops subject pronouns when the verb form already makes the subject clear. So you could also say:

• Se continuar febril, vou à clínica amanhã.

That is natural.

However, including eu can be useful for:

• emphasis
• clarity
• contrast with someone else

For example:

• Se eu continuar febril, vou à clínica amanhã; se tu melhorares, não precisas de ir.

So in your sentence, eu is optional, but perfectly fine.

Portuguese uses definite articles more often than English does.

So where English might say:

• go to hospital
• go to the clinic

Portuguese often says:

• ir ao hospital
• ir à clínica

The article sounds natural here because you are referring to the place as a known type of destination.

Leaving out the article would usually sound incomplete or unnatural in this sentence.

Yes. Portuguese word order is fairly flexible, though some positions sound more natural than others.

Possible versions include:

• Se eu continuar febril, vou à clínica amanhã.
• Amanhã, se eu continuar febril, vou à clínica.
• Se eu continuar febril amanhã, vou à clínica.
  This one can slightly suggest that the feverish condition is specifically being checked tomorrow.

The original sentence is very natural because amanhã clearly modifies the planned trip to the clinic.

Not exactly.

• clínica usually means clinic
• hospital means hospital

A clínica may be:

• a private medical clinic
• a smaller healthcare centre
• a specialised practice

So the sentence suggests going to a clinic, not necessarily a full hospital.

This matters because Portuguese often distinguishes these places quite clearly:

• Vou ao hospital.
• Vou à clínica.
• Vou ao centro de saúde.

Yes, and it changes the nuance slightly.

• Se eu continuar febril = if I continue to be feverish / if I remain feverish
• Se eu estiver febril = if I am feverish

So continuar emphasizes that the fever is already happening now and may persist.

By contrast, estiver only focuses on the condition at that future moment.

Examples:

• Se eu continuar febril, vou à clínica amanhã.
  The fever is already present now.
• Se eu estiver febril amanhã, vou à clínica.
  I may or may not have a fever tomorrow.

Because Portuguese does not normally use vou + infinitive after se in this kind of future condition.

After se for a real future possibility, the normal form is the future subjunctive:

• Se eu continuar febril...

Not:

• Se eu vou continuar febril...

This is one of the key differences from English, where learners may be tempted to translate directly from if I am going to continue...

In Portuguese, the structure is simpler and more idiomatic:

• Se eu continuar...

It is mostly neutral, but febril makes it sound a little more formal or medical.

So the sentence feels like something you could see in:

• careful speech
• written language
• a health-related context

A more everyday version might be:

• Se eu continuar com febre, vou à clínica amanhã.

That sounds slightly more conversational.

Both are correct. The difference is mainly in tone.