عندي ألم في الأسنان، ولذلك أذهب إلى الصيدلية الآن.

Arabic does not usually use a separate verb like English have in sentences like this.

• عندي literally means at me or with me.
• It is made of:
  • عند = at / with / in the possession of
  • ي = my / me

So:

• عندي ألم = I have pain
• literally: At me is pain

This is a very common Arabic way to express possession or a condition:

• عندي كتاب = I have a book
• عندي مشكلة = I have a problem

In normal Arabic writing, short vowel endings are usually not written.

So the word appears as:

• ألم

But in fully vocalized Classical/MSA grammar, it would often be:

• أَلَمٌ

That final -un is the nominative ending for an indefinite noun when it functions as the main noun in this kind of sentence.

In everyday printed Arabic, those case endings are usually omitted, so learners normally see just:

• عندي ألم

Both are possible, but they are slightly different in feel.

• في الأسنان = in the teeth / in my teeth from context
• في أسناني = in my teeth explicitly

In Arabic, body parts are often understood from context, so the definite form الأسنان can sound natural even when English would say my teeth.

So:

• عندي ألم في الأسنان = natural MSA
• عندي ألم في أسناني = also correct, and more explicitly my teeth

Arabic often expresses this idea as pain in the teeth rather than using one single word like English toothache.

• ألم = pain
• في الأسنان = in the teeth

So the whole phrase is literally:

• pain in the teeth

This is a normal Arabic way to express dental pain. You may also hear other medical-style expressions, but this one is straightforward and common for learners.

ولذلك means and therefore, so, or for that reason.

It is made of two parts:

• و = and
• لذلك = therefore / for that reason / because of that

So:

• عندي ألم في الأسنان، ولذلك أذهب... = I have tooth pain, and therefore I am going...

You can also sometimes see just:

• لذلك = therefore
• without the و

In Arabic, the present tense often covers both:

• simple present: I go
• present progressive: I am going

Context tells you which meaning is intended.

Because the sentence includes:

• الآن = now

the meaning becomes clearly:

• I am going now

So أذهب here is present tense in form, but in meaning it works like English am going.

إلى means to and is the normal preposition for movement toward a place.

• أذهب إلى الصيدلية = I go to the pharmacy

This is the standard pattern:

• أذهب إلى المدرسة = I go to school
• أذهب إلى البيت = I go home / to the house

So إلى is there because the verb أذهب usually takes إلى when you say where you are going.

Both can be grammatical, but the definite form often sounds more natural here.

• الصيدلية = the pharmacy
• صيدلية = a pharmacy

In many real situations, if you are going to get medicine, Arabic often uses the definite noun in the same way English might say:

• I’m going to the pharmacy

So:

• أذهب إلى الصيدلية = I am going to the pharmacy

In Arabic, the subject pronoun is often already included in the word itself, so it can be omitted.

In this sentence:

• عندي already includes ي = me / my
• أذهب begins with أ-, which marks I in the present tense

So أنا is not necessary.

Compare:

• أذهب = I go
• أنا أذهب = I go but with extra emphasis

Arabic often leaves out the separate pronoun unless it is needed for emphasis, contrast, or clarity.

أذهب is the first-person singular present-tense form of the verb ذهب = to go.

Breakdown:

• past/root verb: ذهب
• present I go: أذهب

The prefix أ in the present tense commonly marks I.

Some related forms are:

• أذهب = I go
• تذهب = you go or she goes
• يذهب = he goes
• نذهب = we go

So in this sentence:

• أذهب إلى الصيدلية الآن = I am going to the pharmacy now

الآن means now, and it makes the time reference explicit.

With it:

• أذهب إلى الصيدلية الآن = I am going to the pharmacy now

Without it:

• أذهب إلى الصيدلية could mean
  • I go to the pharmacy
  • I am going to the pharmacy depending on context

So الآن helps make the sentence feel immediate and present.

A fully vocalized version could be written as:

• عِندِي أَلَمٌ فِي الأَسْنَانِ، وَلِذَلِكَ أَذْهَبُ إِلَى الصَّيْدَلِيَّةِ الآنَ.

A few notes:

• عِندِي = ʿindī
• أَلَمٌ = pain
• الأَسْنَانِ after في takes genitive in full grammar
• أَذْهَبُ = I go
• الصَّيْدَلِيَّةِ after إلى is also genitive
• الآنَ is often read with fatḥa

In ordinary writing, those endings are usually omitted.

A simple learner-friendly transliteration is:

• ʿindī alam fī al-asnān, wa-li-dhālika adhhabu ilā aṣ-ṣaydaliyyati al-ān

A smoother pronunciation guide:

• ʿin-dee a-lam fee al-as-naan, wa-li-dhaa-li-ka adh-ha-bu i-laa as-say-da-liy-ya-ti al-aan

A couple of pronunciation points:

• ع in عندي is a consonant that has no exact English equivalent.
• In الصيدلية, the ل of ال is absorbed because ص is a sun letter, so it sounds like aṣ-ṣaydaliyya, not al-ṣaydaliyya.

Yes. A learner may also see or use:

• لذلك = therefore / for that reason
• فَلِذَلِكَ or simply فـ in some contexts = so / therefore
• لذا = thus / therefore in formal style

For example:

• عندي ألم في الأسنان، لذلك أذهب إلى الصيدلية الآن.
• عندي ألم في الأسنان، فأذهب إلى الصيدلية الآن.

All of these express cause and result, though ولذلك is very clear and easy for learners.

Yes, it is natural and clear in MSA.

In spoken Arabic, people might choose more everyday phrasing depending on the dialect. For example, they may:

• use a dialect word for now
• use a different connector instead of ولذلك
• say my teeth more explicitly
• use a different way to say I’m going

But as Modern Standard Arabic, the sentence is perfectly good and understandable:

• عندي ألم في الأسنان، ولذلك أذهب إلى الصيدلية الآن.

It is a solid example of formal, correct Arabic.