Si el picor no se me pasa, la farmacéutica dice que no debo tocarme la ampolla.

Because si without an accent means if.

• si = if
• sí = yes

So Si el picor no se me pasa... means If the itching doesn’t go away...

Picor means itching or an itchy sensation.

It comes from the verb picar, which can mean to sting, to itch, or to be spicy, depending on context.

In this sentence, el picor is the feeling of itchiness, not the action of scratching.

Pasarse is a very common way to say that a symptom or feeling goes away.

So:

• Se me pasa = it goes away for me / it stops bothering me
• No se me pasa = it doesn’t go away

The pronouns work like this:

• se pasa = goes away
• me = for me / on me / to me, depending on context

So el picor no se me pasa is an idiomatic Spanish way to say the itching doesn’t go away.

The me shows who is affected by the symptom.

Compare:

• Se pasa = it goes away
• Se me pasa = it goes away for me
• Se te pasa = it goes away for you
• Se le pasa = it goes away for him/her

Spanish often uses this kind of structure with physical sensations, symptoms, and emotions.

Here la farmacéutica means the female pharmacist.

The word farmacéutico / farmacéutica can mean:

• pharmacist (a person)
• pharmaceutical (as an adjective, in some contexts)

In this sentence, because it has the article la and refers to someone who says something, it clearly means the pharmacist.

After decir que, Spanish normally uses the indicative when reporting what someone says as information.

So:

• dice que no debo tocarme la ampolla = she says that I mustn’t / shouldn’t touch the blister

Here debo is the present indicative of deber.

You might see the subjunctive after other expressions, especially with influence or doubt, but decir que by itself usually takes the indicative in this kind of statement.

Debo comes from deber and can mean several things depending on context:

• I must
• I should
• I ought to

In no debo tocarme la ampolla, it usually sounds like I shouldn’t touch the blister or I mustn’t touch the blister.

The exact strength depends on tone and context. Since this is medical advice, it can sound fairly strong.

Because with an infinitive, object/reflexive pronouns are often attached to the end.

So both of these are possible in many contexts:

• no debo tocarme la ampolla
• no me debo tocar la ampolla

But attaching the pronoun to the infinitive is very common and often sounds smoother.

So:

• tocarme = to touch myself / to touch on myself

Here it means to touch my blister.

Yes, it is effectively reflexive here because the person is touching their own body.

Spanish often uses a reflexive pronoun when someone does something to themself:

• lavarme las manos = to wash my hands
• cortarme el dedo = to cut my finger
• tocarme la ampolla = to touch my blister

Even though the direct object is la ampolla, the me shows that the blister is on my body.

Spanish often uses the definite article with body parts and things on the body when the owner is already clear.

So instead of saying my blister, Spanish naturally says the blister, while the pronoun me shows whose it is:

• tocarme la ampolla = touch my blister
• literally: touch myself the blister

This is very common in Spanish:

• me duele la cabeza = my head hurts
• me lavo las manos = I wash my hands

Yes, ampolla can have different meanings depending on context, including:

• blister on the skin
• ampoule / vial in medical contexts
• sometimes a type of bottle or bulb in technical contexts

Here, because of picor and no debo tocarme, it clearly means blister.

The sentence begins with the condition:

• Si el picor no se me pasa = If the itching doesn’t go away

Then it gives the main statement:

• la farmacéutica dice que no debo tocarme la ampolla = the pharmacist says I shouldn’t touch the blister

This is a very normal structure in Spanish:

• Si + present, present
• Si llueve, no salgo.
• Si no se me pasa, voy al médico.

So the order is natural and matches English quite closely.