Если уж сомневаешься, бронхит это или ангина, то лучше не лечиться наугад, а показать горло врачу.

Here уж adds emphasis. It is hard to translate with one fixed English word, but in this sentence it gives something like:

• if you really are in doubt
• if you do have doubts
• if you’re unsure anyway

So если сомневаешься is simply if you’re unsure, while если уж сомневаешься sounds a bit stronger and more pragmatic: if it has already come to the point that you’re not sure, then...

It often suggests: since that is the case, the sensible next step is obvious.

Not necessarily. Russian often uses the 2nd person singular for general advice, just like English can use you in a general sense:

• If you’re unsure, don’t guess.
• When you feel sick, you should see a doctor.

So сомневаешься here means something like if you are in doubt / if one is in doubt. It is addressing the listener directly, but it can also be read as general advice.

Because Russian usually omits subject pronouns when the verb ending already shows the person and number.

• сомневаешься already means you doubt / you are unsure
• so ты is unnecessary unless you want extra emphasis or contrast

That is very normal in Russian.

Yes, this is a somewhat compressed, conversational structure.

The idea is:

• сомневаешься, бронхит это или ангина
• you’re unsure whether it’s bronchitis or tonsillitis

A fuller version might be:

• сомневаешься, бронхит это или ангина
• сомневаешься, что это — бронхит или ангина
• сомневаешься, бронхит это у тебя или ангина

So this is an elliptical way of saying whether it is bronchitis or tonsillitis.

Russian often allows this kind of shortened structure in speech and informal writing.

Here это is part of an identifying pattern, similar to this is / it is.

Compare:

• Это бронхит. — It’s bronchitis.
• Это ангина. — It’s tonsillitis.

Inside the indirect question, это helps express is it bronchitis or tonsillitis?

The word order is a bit unusual for English speakers, but the meaning is essentially:

• бронхит это или ангина?
• is it bronchitis or tonsillitis?

So это is not the subject this in the literal English sense; it works more like it is in an identification sentence.

This is the common correlative pattern если ..., то ... — if ..., then ...

• Если сомневаешься, то лучше...

In Russian, то is often optional, especially in casual speech, but it is very common and natural. It helps mark the second part of the sentence clearly.

So:

• Если сомневаешься, лучше... — also possible
• Если сомневаешься, то лучше... — slightly more structured and explicit

Лучше can be used predicatively to mean it is better to...

So:

• лучше не лечиться наугад — it’s better not to treat yourself by guessing
• а показать горло врачу — but to have a doctor look at your throat / to show your throat to a doctor

This is a very common Russian pattern:

• Лучше подождать. — It’s better to wait.
• Лучше не спорить. — It’s better not to argue.

No extra verb like is is needed in the present tense.

Лечить means to treat/cure something or someone.

• лечить бронхит — to treat bronchitis

Лечиться means to undergo treatment / to treat oneself / to be getting treated.

In this sentence, не лечиться наугад means:

• not to try to treat yourself by guessing
• not to self-medicate blindly

The -ся makes it about the person receiving the treatment, often effectively getting treatment or treating oneself.

Because the sentence contrasts two different kinds of actions:

• не лечиться наугад — an ongoing or general activity to avoid
• показать горло врачу — a single concrete action that is recommended

So:

• лечиться imperfective = to be treating oneself / to engage in treatment
• показать perfective = to show once, as a practical next step

This is very natural aspect usage in Russian: avoid the ongoing wrong approach, do the one sensible action.

Наугад means at random, by guesswork, blindly, without knowing for sure.

So не лечиться наугад means:

• don’t treat yourself by guessing
• don’t self-medicate without knowing what the illness actually is

It often has the idea of acting without enough information.

The pattern не X, а Y means not X, but Y.

Here:

• не лечиться наугад, а показать горло врачу
• not treat yourself blindly, but show your throat to a doctor

This structure sets up a contrast between:

1. the wrong or less suitable action
2. the better alternative

That is exactly what не..., а... is often used for.

Yes, literally it is to show your throat to a doctor.

In natural English, depending on context, you might say:

• have a doctor look at your throat
• let a doctor examine your throat

Russian often uses показать + body part + doctor/person where English may prefer have someone examine.

So the Russian phrasing is completely normal.

Because показать кому? что? takes:

• what in the accusative
• to whom in the dative

So:

• показать горло — show the throat
• врачу — to the doctor

That is why it is врачу, not врач.

Yes. Both are possible:

• показать горло врачу
• показать врачу горло

Russian word order is flexible. The difference is mostly about emphasis and information flow.

• показать горло врачу keeps горло closer to the verb and may sound slightly more neutral here
• показать врачу горло highlights the recipient earlier

In this sentence, the original order sounds very natural.

It could, but it would mean something slightly different.

• идти к врачу — go to the doctor
• показать горло врачу — show your throat to the doctor / have the doctor look at your throat

The original is more specific: not just visiting a doctor in general, but getting the throat examined.

It is fairly natural everyday Russian, closer to practical spoken advice than to formal medical writing.

Things that make it feel conversational include:

• the emphatic уж
• the compressed structure бронхит это или ангина
• the direct practical advice format

A more formal version might spell things out more fully, but this sentence is perfectly normal and idiomatic.