Se eu tivesse colocado um curativo antes, a ferida no calcanhar não teria ardido tanto.

This is the standard Portuguese pattern for a past unreal condition—the equivalent of English If I had put... it wouldn’t have hurt/stung so much.

The structure is:

• Se + pluperfect subjunctive: se eu tivesse colocado
• conditional perfect: não teria ardido

So the sentence describes:

• something that did not happen in the past
• and an imagined result that also did not happen

It is the Portuguese equivalent of the English third conditional.

Tivesse colocado is a compound subjunctive form.

It is made of:

• tivesse = imperfect subjunctive of ter
• colocado = past participle of colocar

Together, tivesse colocado means had put / had placed in an unreal or hypothetical past context.

Compare:

• Eu coloquei = I put / I placed
• Eu tinha colocado = I had put
• Se eu tivesse colocado = if I had put

That last one is used after se when the situation is hypothetical and did not actually happen.

Teria ardido is the conditional perfect.

It is formed with:

• teria = conditional of ter
• ardido = past participle of arder

It means would have burned / would have stung / would have hurt.

So:

• ardeu = it burned / stung
• teria ardido = it would have burned / stung

In this sentence, it expresses the imagined result of the unreal condition:

• If I had put on a bandage earlier, the wound wouldn’t have stung so much.

Curativo is a general word for a dressing, bandage, or wound covering.

Depending on context, it can mean:

• a small adhesive bandage
• a dressing on a wound
• a bandage in a broader sense

If you want to be very specific about Band-Aid, Brazilians often say:

• band-aid
• curativo adesivo

So um curativo here is natural, but it is slightly more general than the brand-name idea of a Band-Aid.

No is the contraction of:

• em + o = no

So:

• no calcanhar = on the heel / in the heel area

And a ferida no calcanhar means:

• the wound on the heel

This is very common in Portuguese:

• a dor no braço = the pain in the arm
• um corte no dedo = a cut on the finger
• uma ferida no pé = a wound on the foot

Portuguese often uses definite articles more naturally than English does.

So a ferida literally means the wound, and it sounds natural because the wound is being treated as a specific, known wound—the one on the heel.

In English, we might sometimes say:

• the wound
• or simply my wound

Portuguese often prefers the definite article in these cases.

Yes, but in this context arder usually means something like:

• to sting
• to burn
• to smart
• sometimes to hurt with a burning sensation

For a wound, blister, scrape, or irritated skin, arder is very common in Brazilian Portuguese.

Examples:

• A ferida está ardendo. = The wound is stinging/burning.
• Meu olho está ardendo. = My eye is burning/stinging.
• Isso ardeu muito. = That stung a lot.

So here não teria ardido tanto means wouldn’t have stung/burned so much.

Tanto here means so much or that much.

It modifies the idea of intensity:

• não teria ardido tanto = wouldn’t have stung so much

Putting it at the end is very natural in Portuguese.

Similar examples:

• Não doeu tanto. = It didn’t hurt that much.
• Eu não esperei tanto. = I didn’t wait that long.
• Ela não trabalhou tanto assim. = She didn’t work that much.

So tanto is acting like an adverb of degree here.

Yes. Portuguese often drops subject pronouns when the verb already makes the subject clear.

So both are possible:

• Se eu tivesse colocado um curativo antes...
• Se tivesse colocado um curativo antes...

Including eu can add:

• emphasis
• clarity
• contrast

Without eu, the sentence still sounds natural in conversation, especially if the subject is already obvious from context.

Yes. In this sentence, antes means:

• earlier
• before
• beforehand

So um curativo antes means a bandage earlier / beforehand.

A few similar possibilities:

• mais cedo = earlier
• antes disso = before that
• com antecedência = in advance

But antes is the simplest and most natural choice here.

Yes, it is natural and grammatically solid.

A Brazilian might also say slightly different versions depending on style and context, for example:

• Se eu tivesse colocado um curativo antes, a ferida no calcanhar não teria ardido tanto.
• Se eu tivesse colocado um band-aid antes, não teria ardido tanto.
• Se eu tivesse coberto a ferida antes, ela não teria ardido tanto.

The original sentence sounds correct and natural, especially in careful spoken or written Portuguese.

Because after ter in compound tenses, the past participle normally does not agree with the subject.

So you say:

• a ferida teria ardido
• os olhos teriam ardido
• as mãos teriam ardido

The participle stays the same: ardido

This is different from uses with ser or estar, where agreement can happen in other structures, but with ter + participle in a tense like this, no agreement is made.