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Prepositions after verbs

Complicate by, for, in, with or about?

Complicate is usually followed by with when something makes a situation harder. Other prepositions may appear in different sentence structures, but they are not standard fixed combinations with complicate.

Quick answer

Which preposition is used with complicate?

The most common pattern is complicate something with something. You can also use by after a passive form to show the cause: be complicated by. Prepositions such as for, in, and about are usually part of another phrase, not fixed combinations with complicate.

The illness was complicated by an infection.
Don't complicate the issue with unnecessary details.
The report complicated matters with conflicting data.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
complicate something with + detail/problem

Adding something that makes a situation harder

Use with to introduce the thing that creates extra difficulty.

They complicated the process with too many rules.
She complicated the discussion with legal terminology.
2
be complicated by + cause

Showing what caused extra difficulty

In passive sentences, by introduces the factor that made the situation more difficult.

The rescue effort was complicated by heavy rain.
Negotiations were complicated by political tensions.
3
complicate matters with + action

Describing actions that worsen a situation

This pattern is common in formal and neutral English.

He complicated matters with a last-minute change.
The company complicated matters with unclear instructions.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
complicate with
They complicated the project with unnecessary features.
Standard pattern for adding something that creates difficulty.
complicated by
The journey was complicated by bad weather.
Standard passive pattern showing the cause of difficulty.
complicate for
The new rule complicated the process for new employees.
For introduces the affected person, not a fixed verb-preposition combination.
complicate in
She was involved in a case complicated in several ways.
In is usually part of another phrase and is not a standard complement after complicate.
complicate about
They argued about details and complicated the meeting.
About normally belongs to another verb or noun, not directly to complicate.

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Using of after complicate

Complicate is not followed by of in standard English.

✕ The illness complicated of the treatment. ✓ The illness complicated the treatment.

Confusing complicate with complicity

Complicate is a verb meaning make harder, not involvement in wrongdoing.

✕ He was complicated in the crime. ✓ He was complicit in the crime.

Adding unnecessary prepositions

Complicate often takes a direct object without a preposition.

✕ They complicated about the issue. ✓ They complicated the issue with extra demands.

Using by in active sentences incorrectly

By is natural mainly in passive structures.

✕ They complicated by new rules the process. ✓ They complicated the process with new rules.

Quick practice

Choose the expression that matches the intended meaning.

1. The investigation was complicated ___ conflicting evidence.
2. Don't complicate the plan ___ unnecessary changes.
3. The delay complicated the process ___ international students.

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Frequently asked questions

Is complicate with correct?

Yes. Complicate something with something is a standard pattern when extra details or problems are added.

Can I say complicated by?

Yes. Complicated by is very common in passive sentences to explain what caused the difficulty.

Is complicate about natural English?

Usually no. About is generally part of another phrase rather than a normal complement after complicate.

calculate, by, calculate, in, calculate, from "call for" or "call on"? "campaign for" or "campaign against"? cancel by, due, at, in or for? capitulate to, in, like, by or after? captivate by, for, with, from or in? "capture by" or "capture in"? "care about" or "care for"? carry with, by, in, to or into? carve into, out, in, on or with? cast in, into, for, by or on? "catch in", "catch by" or "catch on"?

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