Learn Hardcore German: Wenn ich Kopfschmerzen habe, trinke ich viel Wasser und mache eine kurze Pause. - When I have a headache, I drink a lot of water and take a short break.

In German, subordinate clauses (Nebensätze) with conjunctions like wenn, dass, weil, obwohl, etc. put the conjugated verb at the very end of the clause.

Wenn ich Kopfschmerzen habe
– wenn = subordinating conjunction
– ich Kopfschmerzen = middle part
– habe = conjugated verb at the end

So „Wenn ich Kopfschmerzen habe“ literally follows the rule:

conjunction – (subject/objects/other info) – verb.

„Wenn ich habe Kopfschmerzen“ breaks this rule and sounds wrong to native speakers.

Why is it „trinke ich“ instead of „ich trinke“ after the comma?

German main clauses follow the verb‑second (V2) rule: the conjugated verb must be in second position in the clause.

When you start the sentence with a wenn‑clause, that whole clause counts as one element in front of the main clause:

Wenn ich Kopfschmerzen habe, trinke ich viel Wasser …
- First element: Wenn ich Kopfschmerzen habe
- Second element: trinke (verb)
- Then: ich (subject), then objects/adverbs.

If you started with the subject instead, you’d get:

Ich trinke viel Wasser, wenn ich Kopfschmerzen habe.

Both are correct. The position of the wenn‑clause changes the word order of the main clause, but the verb is always in second position of the main clause.

Why do we use wenn here and not wann or falls?

These three words are easy to mix up:

wenn
- Means “if / whenever / when(ever)” in conditional or repeated-time sentences
- Used here because it introduces a condition:
  Wenn ich Kopfschmerzen habe, trinke ich … = If/whenever I have a headache, I drink…
wann
- Means “when?” in the sense of “at what time?”
- Used in questions and indirect questions:
  - Wann kommst du? – When are you coming?
  - Ich weiß nicht, wann er kommt.
falls
- Also means “if, in case”, but sounds a bit more hypothetical or cautious than wenn.
- Could work here, but the nuance is slightly different:
  - Falls ich Kopfschmerzen habe, trinke ich … = In case I have a headache, I (will) drink… (more like a contingency plan)

In your sentence, wenn is the most natural choice because it describes a general, repeated condition.

Why is the present tense used in both parts instead of something like a future tense?

German uses the present tense (Präsens) much more broadly than English, especially:

for general truths or habits
for future actions when the time is clear from context or a time expression
in conditional sentences with wenn

So:

Wenn ich Kopfschmerzen habe, trinke ich viel Wasser …
can mean:
- If/when I have a headache, I drink a lot of water … (general habit)
- and in context can also be understood like English “If I get a headache, I’ll drink a lot of water …”

German could use Futur I (werde trinken), but often chooses the present instead. Using werde here would sound more formal or emphasize a specific future situation, and is not necessary.

Why is it Kopfschmerzen (plural) and not Kopfschmerz (singular)?

In everyday German, pain is very often expressed in the plural:

Kopfschmerzen haben – to have a headache
Rückenschmerzen haben – to have back pain
Magenschmerzen haben – to have stomach pain

Using the singular Kopfschmerz is possible, but:

it sounds technical, medical, or literary, not like normal everyday speech
most native speakers overwhelmingly say Kopfschmerzen in this context.

So „Ich habe Kopfschmerzen“ is the idiomatic way to say “I have a headache.”

Why is there no article before Wasser in „trinke ich viel Wasser“?

Wasser here is treated as a mass noun (uncountable), similar to English “water” used in a general sense.

In German, mass nouns normally don’t take an article when you mean “some amount of it in general”:

Ich trinke Wasser. – I drink water.
Ich mag Brot. – I like bread.
Er braucht Ruhe. – He needs rest.

When you add quantifiers like viel (a lot of), you still typically do not use an article with mass nouns:

Ich trinke viel Wasser. – I drink a lot of water.
Sie isst viel Brot. – She eats a lot of bread.

You could use an article if you are talking about a specific water:

Ich trinke das Wasser aus der Flasche. – I drink the water from the bottle.

But here, it is just water in general, so no article is used.

Why viel Wasser and not viele Wasser?

In German the choice viel vs. viele depends on whether the noun is treated as uncountable (mass) or countable (plural items).

viel = much / a lot of (for uncountable things)
- viel Wasser, viel Brot, viel Zeit
viele = many / a lot of (for countable plural things)
- viele Flaschen, viele Leute, viele Äpfel

Since you cannot normally count “waters” as separate units in this sentence, Wasser is uncountable, so viel Wasser is correct.

„viele Wasser“ would only make sense in a very unusual, specific context (e.g. several different kinds of water on a menu), and even then people would usually say viele Sorten Wasser.

Why is it eine kurze Pause and how do the endings work?

Let’s break down „eine kurze Pause“:

Pause
- noun, feminine: die Pause
- here it is a direct object → accusative case
eine
- indefinite article, feminine, accusative: eine
- (for feminine nouns, nominative and accusative are both eine)
kurze
- adjective describing Pause
- after an article (eine), in feminine accusative, the adjective takes the ending -e: kurze

Pattern for feminine singular with eine:

Nominative: eine kurze Pause (subject)
Accusative: eine kurze Pause (object)

So in „… trinke ich viel Wasser und mache eine kurze Pause“,
Pause is a direct object, so you get „eine kurze Pause“.

Why do we say „eine Pause machen“ and not something like „eine Pause nehmen“?

This is mostly a matter of collocation (which verbs naturally go with which nouns).

In German, the common expression is:

eine Pause machen – to take a break

You will also see:

eine Pause einlegen – to insert/make a pause (a bit more formal or written)
sich eine Pause gönnen – to allow yourself a break

„eine Pause nehmen“ is understandable but sounds unusual or influenced by English; native speakers almost always say „eine Pause machen“ in everyday speech.

So „mache eine kurze Pause“ is the idiomatic phrasing.

Why is there a comma after „Wenn ich Kopfschmerzen habe“?

German has stricter comma rules than English, especially with clauses.

Rule:
You must put a comma between a subordinate clause and a main clause.

Wenn ich Kopfschmerzen habe, trinke ich viel Wasser …
- Wenn ich Kopfschmerzen habe = subordinate clause (Nebensatz)
- trinke ich viel Wasser und mache eine kurze Pause = main clause (Hauptsatz)

So the comma here is obligatory.

If you reverse the order, you still need a comma:

Ich trinke viel Wasser und mache eine kurze Pause, wenn ich Kopfschmerzen habe.

Why is there no comma before „und“ in „… trinke ich viel Wasser und mache eine kurze Pause“?

At the end, you have:

trinke ich viel Wasser und mache eine kurze Pause

This is one main clause with the subject ich and two verbs sharing that subject:

Subject: ich
Verb 1: trinke
Object 1: viel Wasser
Verb 2: mache
Object 2: eine kurze Pause

In German, when two verbs share the same subject in one clause, you generally don’t put a comma before und:

Ich esse und trinke.
Er liest ein Buch und hört Musik.

If you explicitly repeat the subject, they become two main clauses, and then you can/must use a comma:

…, trinke ich viel Wasser, und ich mache eine kurze Pause.
(less natural here, but grammatically possible)

Why is „Wenn“ capitalized? Is it always written with a capital W?

In your sentence, Wenn is at the very beginning of the sentence, so it is capitalized because of the normal rule:

The first word of a sentence is capitalized in German.

As a word type, wenn is a conjunction and is otherwise written with a lowercase w:

Ich komme, wenn ich Zeit habe.
Wenn es regnet, bleiben wir zu Hause.

So:

Wenn at the beginning of a sentence → capital W (position rule)
wenn in the middle of a sentence → lowercase (it’s not a noun)

Can I add „dann“ to say „then I drink a lot of water“? Where would it go?

Yes, you can add dann to make the consequence more explicit:

Wenn ich Kopfschmerzen habe, dann trinke ich viel Wasser und mache eine kurze Pause.

Common placements:

Directly after the comma, before the verb (most usual):
- Wenn ich Kopfschmerzen habe, dann trinke ich viel Wasser …
Less common, but possible, after the verb:
- Wenn ich Kopfschmerzen habe, trinke ich dann viel Wasser …
  (emphasis shifts slightly to what I do in that situation)

But the natural, standard version is:

Wenn ich Kopfschmerzen habe, dann trinke ich viel Wasser und mache eine kurze Pause.

Can I also say „Ich trinke viel Wasser und mache eine kurze Pause, wenn ich Kopfschmerzen habe“? Is there a difference?

Yes, that sentence is completely correct:

Ich trinke viel Wasser und mache eine kurze Pause, wenn ich Kopfschmerzen habe.

The meaning is basically the same. The difference is mostly in emphasis and flow:

Wenn ich Kopfschmerzen habe, trinke ich …
→ emphasizes the condition first (Whenever / If I have a headache…)
Ich trinke viel Wasser und mache eine kurze Pause, wenn ich Kopfschmerzen habe.
→ starts with what you do, then adds when you do it.

Both word orders are very natural in German.