Learn Hardcore Finnish: Jos kipu pahenee yöllä, soitan päivystykseen heti. - If the pain gets worse at night, I call the emergency clinic immediately.

Kun kipu pahenee, soitan päivystykseen.
= When(ever) the pain gets worse, I call / I’ll call the emergency service.
(It’s treated as something expected or repeated.)

In a sentence like yours, jos is better because the speaker is not sure whether the pain will actually worsen.

Why is there a comma after yöllä? Do you always put a comma before the main clause in Finnish?

Yes, in standard Finnish orthography you normally put a comma between a dependent clause and the main clause.

Here, jos kipu pahenee yöllä is a subordinate clause (introduced by jos), and soitan päivystykseen heti is the main clause. Finnish rules say you separate them with a comma:

Jos kipu pahenee yöllä, soitan päivystykseen heti.
Soitan päivystykseen heti, jos kipu pahenee yöllä.

The comma is used both ways, even if English wouldn’t always use one. So yes, with jos, kun, että, jotta, etc., you normally see a comma between that clause and the main clause.

What form is kipu in, and why isn’t it inflected? Could it be kivun?

Kipu is in the nominative singular, the “dictionary form” of the noun, and it works as the subject of the sentence:

kipu pahenee = the pain gets worse

You’d use kivun (genitive) if kipu were possessing something or used in a different syntactic role, for example:

kivun paheneminen = the worsening of the pain
kivun syy = the cause of the pain

Here we simply say that pain gets worse, so nominative kipu is correct.

Also, note vocabulary:

kipu = pain (more neutral/medical)
särky = ache (often used for specific areas, e.g. päänsärky = headache)

You could also say:

Jos särky pahenee yöllä, soitan päivystykseen heti.

but kipu is very natural in a general or medical context.

What exactly is pahenee grammatically, and how is it formed?

Pahenee is the 3rd person singular present tense of the verb pahentua (to get worse, to worsen).

Dictionary form: pahentua
Stem: pahene-
Conjugation (present):
- minä pahenen – I get worse
- sinä pahenet – you get worse
- hän / se pahenee – he/she/it gets worse
- kipu pahenee – the pain gets worse

So in the sentence:

kipu pahenee = the pain gets worse / is getting worse

You could also express the idea with an adjective and tulla:

kipu tulee pahemmaksi = the pain becomes worse

but kipu pahenee is shorter and very natural.

Why is soitan in the present tense even though it refers to the future in English (“I’ll call”)?

Finnish does not have a separate future tense. The present tense often covers both present and future, and context shows which one is meant.

Soitan päivystykseen heti.
- literally: I call the emergency service immediately.
- in this context: I’ll call / I’m going to call the emergency service immediately.

Time references (jos, huomenna, yöllä, etc.) tell you that the action is in the future. So Finnish uses the present tense, and English often translates it with will or going to.

Why don’t we use the conditional soittaisin after jos? Would Jos kipu pahenee yöllä, soittaisin päivystykseen heti be wrong?

Soittaisin is the conditional form of soittaa and usually corresponds to I would call.

Jos kipu pahenee yöllä, soitan päivystykseen heti. = If the pain gets worse at night, I will call the emergency service immediately.
→ This is a real plan / promise.
Jos kipu pahenee yöllä, soittaisin päivystykseen heti. = If the pain got worse at night, I would call the emergency service immediately.
→ This sounds more hypothetical or less certain, and in many contexts you’d expect a second clause explaining why you would but maybe can’t.

For a simple, straightforward intention (“I will do X if Y happens”), Finnish most often uses the present indicative (soitan), not the conditional.

What does päivystykseen mean exactly, and what is the base word?

The base word is päivystys, which broadly means on‑call service / emergency duty. In a medical context, päivystys is:

the emergency department or emergency clinic
or the emergency duty service (sometimes a phone number, sometimes a physical place)

Päivystykseen is the illative case of päivystys, meaning into / to the emergency department/service.

So:

Soitan päivystykseen.
literally: I call to the emergency department.
natural English: I’ll call the emergency service / emergency department.

Other related words:

hätäkeskus = emergency response centre (e.g. 112 in Finland)
ensiapu = first aid, emergency (often a first‑aid clinic / ER name)

Why is päivystykseen in the illative case? Could it be päivystykseen vs päivystykselle or päivystyksessä?

Päivystykseen is the illative (direction into / to) and is the normal choice for a destination with a verb of motion or transfer (including mental/communication “motion” like calling):

mennä päivystykseen = go to the emergency department
ajaa päivystykseen = drive to the emergency department
soittaa päivystykseen = call the emergency department

The other cases would change the meaning:

päivystykselle (allative) = to the surface/benefit of something; sometimes used with “to someone”, but not the usual phrase here.
päivystyksessä (inessive) = in/at the emergency department (location, not movement)

So for the idea “call to X (as a service/place)”, soittaa + illative (päivystykseen) is standard.

What does yöllä literally mean, and why is it in that form?

Yöllä is the adessive form of yö (night), and with time expressions the adessive often means “at [time]”:

yöllä = at night
päivällä = in the daytime
aamulla = in the morning
illalla = in the evening

So:

Jos kipu pahenee yöllä = If the pain gets worse at night

Forms you might see:

yö (nominative) = night (as a basic noun)
yönä (essive) = as a night / on (a particular) night – used in more specific contexts, e.g. sinä yönä = on that night

For general “at night”, yöllä is the standard expression.

Can I change the word order and say Soitan päivystykseen heti, jos kipu pahenee yöllä? Does it change the meaning?

Yes, you can absolutely say:

Soitan päivystykseen heti, jos kipu pahenee yöllä.

The basic meaning is the same. Finnish word order is quite flexible, especially with clause order. The difference is mostly about focus:

Jos kipu pahenee yöllä, soitan...
→ Emphasizes the condition first (“If this happens, then I’ll do that”).
Soitan... jos kipu pahenee yöllä.
→ Starts with the decision/action, then mentions the condition.

Both are very natural here.

Can I say Soitan heti päivystykseen instead of Soitan päivystykseen heti? Where do adverbs like heti usually go?

Yes, both are correct:

Soitan päivystykseen heti.
Soitan heti päivystykseen.

The neutral, very common pattern is:

[subject] + [verb] + [other elements] + [adverb]

but adverbs like heti (immediately), nyt (now), usein (often) can move around quite freely. The position can slightly affect emphasis:

Soitan heti päivystykseen. – a bit more emphasis on the immediacy.
Soitan päivystykseen heti. – slightly more neutral, describing where you call and that you do it immediately.

In normal speech, both versions sound fine and natural.

How do you pronounce tricky parts like yöllä and päivystykseen?

Key points:

Stress: Always on the first syllable of each word.
- JOS KI‑pu PA‑he‑nee YÖL‑lä, SOI‑tan PÄI‑vys‑tyk‑seen HE‑ti.
Long vowels/consonants:
- pahenee: the ee is long, like “eh‑eh”.
- yöllä: the ll is long; hold it slightly: yöl‑lä.
- päivystykseen: the ee at the end is long again.
Special vowels:
- ö in yöllä: rounded front vowel, like the “u” in British nurse but with rounded lips.
- ä in päivystykseen: like the “a” in cat.
Diphthongs:
- päi in päivystykseen: like “pae” in Paella but short and smooth.
- oi in soitan: like boy without the “b”.
-ksen- in päivystykseen:
- pronounced [k‑sen], not as two separate syllables “kə‑sen”. The k and s are just next to each other: päi‑vys‑tyk‑seen.

Could I say jos kipuni pahenee yöllä instead of jos kipu pahenee yöllä?

You can say jos kipuni pahenee yöllä (if my pain gets worse at night), but in practice:

jos kipu pahenee yöllä is more neutral and common, especially in medical contexts where it’s obvious you’re talking about your pain.
Finnish often leaves out possessive endings when the owner is clear from context.

Use kipuni when you really want to highlight ownership or contrast:

Kipuni pahenee yöllä, mutta sinun kipusi pahenee aamulla.
My pain gets worse at night, but your pain gets worse in the morning.

In your sentence, jos kipu pahenee yöllä is the most natural choice.

Is heti formal enough, or should I use something like välittömästi in a medical or formal context?

Heti is perfectly fine and common in both everyday speech and neutral/formal contexts. It simply means immediately / right away.

Soitan päivystykseen heti. – completely natural in any setting.

Välittömästi is a bit more formal / bureaucratic:

Soitan päivystykseen välittömästi.

You might see välittömästi in written instructions or official documents, but in spoken language and normal writing (even medical conversations), heti is very natural and not informal in a negative way.