[alexlearner]

I would like to make up two sentences with the adverb, severely.

(1) Stress made him lose his hair severely.

(2) Their lack of business experience made them lose money severely.

Am I using "severely" correctly in these sentences? Thanks.

[susan53]

No. Severely doesn't fit either of these contexts.It can be used as an adverb of manner :
He spoke to her severely.

but here you are using it as an intensifier for an entire clause - and if you look at a concordancer you'll see that it is used mainly to intensify an individual verb or adjective - eg :

This would severely limit our capacity to...
The two modes were kept severely distinct.

I would rewrite your sentences as :
1. Stress caused him to suffer from severe hair loss.
2. Their lack of experience led to a severe loss of money.

Notice that I've here changed to the adjective severe so that I can use it to premodify/intensify the noun phrase. I'm no longer trying to use the adverb as an intensifier for the whole clause. If you really want the adverb you might say :

3. Stress caused him to suffer severely from hair loss

but 3 doesn't sound as natural as 1, and I can't think of a natural sounding equivalent for the second sentence.