dahaengiya, keun yeomjeungeun eobsgo gamgi jeungsangman issdago haesseo.

다행이야 means That’s a relief or I’m glad to hear that.

It comes from 다행이다 = to be fortunate / to be a relief.

• 다행이다 is the dictionary form.
• 다행이야 is the casual spoken form.
• In a more polite style, you would say 다행이에요.

So this sentence is in casual speech, probably between family members, friends, or someone speaking informally.

Because 크다 is the dictionary form of the adjective to be big. When a Korean adjective directly modifies a noun, it changes form.

• 크다 → 큰
• 큰 염증 = big/serious inflammation

This is like how English changes structure from is big to big before a noun:

• 염증이 크다 = the inflammation is big/severe
• 큰 염증 = big/severe inflammation

In this medical context, 큰 often means serious or major, not just physically large.

Here, 은 marks 염증 as the topic and also gives a slight contrastive feeling.

• 큰 염증은 없고 = As for any major inflammation, there isn’t any
• It can imply something like: there’s no major inflammation, but...

That fits well with the second part:

• 큰 염증은 없고
• 감기 증상만 있다고 했어

So the sentence contrasts two ideas:

• no major inflammation
• only cold symptoms

If it were 큰 염증이 없고, that would sound a little more neutral and purely descriptive. 은 helps highlight the contrast.

없고 is the connective form of 없다. It means there isn’t..., and... or there isn’t..., but...

So:

• 없다 = to not exist / to not have
• 없고 = not existing, and / not existing, while

In this sentence:

• 큰 염증은 없고 감기 증상만 있다고 했어
• They said there is no major inflammation, and only cold symptoms

The -고 connects the first statement to the second one.

만 means only.

So:

• 감기 증상 = cold symptoms
• 감기 증상만 = only cold symptoms

This emphasizes that the condition is limited to cold symptoms, rather than something more serious.

Compare:

• 감기 증상이 있어 = There are cold symptoms.
• 감기 증상만 있어 = There are only cold symptoms.

-다고 했어 is a very common way to report what someone said. It is indirect/reported speech.

Breakdown:

• 있다 = to exist / to have
• 있다고 = that there is / that it exists
• 했다고 = said that...
• 있다고 했어 = said that there is / said that they have

So:

• 감기 증상만 있다고 했어
• [Someone] said there are only cold symptoms

In context, the omitted speaker is probably a doctor, nurse, or someone who checked the patient.

Because in Korean reported speech, the tense inside the quoted content usually reflects the original statement being reported.

Here, the reported content is:

• 큰 염증은 없고 감기 증상만 있다
• There is no major inflammation, and there are only cold symptoms

Then the speaker adds:

• ...고 했어
• ...said

So the whole thing becomes:

• 큰 염증은 없고 감기 증상만 있다고 했어
• They said there is no major inflammation and only cold symptoms

Even though 했어 is past tense, that just means the act of saying happened in the past. The medical condition itself is presented as current.

Korean often omits subjects when they are obvious from context.

So in this sentence, Korean does not explicitly say who said it. Depending on context, it could mean:

• the doctor said
• the nurse said
• they said
• the hospital said
• someone said

This is very normal in Korean. If the listener already knows who is being talked about, the subject is usually left out.

Not exactly.

염증 means inflammation. That is a medical term for swelling or irritation in the body. Inflammation can happen because of infection, but the two are not identical.

• 염증 = inflammation
• 감염 = infection

So 큰 염증은 없고 means there is no major inflammation, not necessarily there is no infection.

Because Korean very often reports speech grammatically instead of with quotation marks.

Instead of writing something like:

• They said, There is no major inflammation...

Korean commonly uses forms like:

• ...다고 했어
• ...라고 했어
• ...냐고 했어

So 있다고 했어 already tells you that this is reported speech. Quotation marks are possible in writing, but they are not necessary.

Yes. A very natural English translation would be something like:

• That’s a relief. They said there’s no major inflammation, just cold symptoms.
• What a relief—they said it’s nothing serious, just cold symptoms.

The Korean sentence is not overly formal, so a natural English translation usually sounds conversational too.

It is in casual informal speech.

You can tell from:

• 다행이야 instead of 다행이에요
• 했어 instead of 했어요

A more polite version would be:

• 다행이에요, 큰 염증은 없고 감기 증상만 있다고 했어요.

So the original sentence is appropriate for informal conversation.