यह दवा खाली पेट नहीं लेनी है।

A word-by-word breakdown is:

• यह = this
• दवा = medicine
• खाली पेट = on an empty stomach
  
  • literally: empty stomach
• नहीं = not
• लेनी = to take, in a form that agrees with a feminine noun
• है = is

So the whole sentence means something like:

This medicine is not to be taken on an empty stomach
or
You should not take this medicine on an empty stomach

Hindi often uses noun phrases where English uses a prepositional phrase.

• खाली = empty
• पेट = stomach

So खाली पेट literally means empty stomach, but idiomatically it means:

• on an empty stomach
• without eating first

This is a very common expression in Hindi, especially in medical instructions.

Examples:

• यह दवा खाली पेट लेनी है। = This medicine should be taken on an empty stomach.
• खाली पेट चाय मत पियो। = Don’t drink tea on an empty stomach.

In Hindi, नहीं usually comes before the verb phrase that it negates.

Here, the verb part is लेनी है, so the negative comes before it:

• नहीं लेनी है = is not to be taken

This is normal Hindi word order.

Compare:

• मुझे नहीं जाना है। = I do not have to go / I am not supposed to go.
• यह काम नहीं करना है। = This work is not to be done.

So in your sentence, नहीं is simply negating the action of taking the medicine.

Because दवा is a feminine noun.

In this kind of construction, the verbal form often agrees with the thing being done or taken. Since:

• दवा is feminine,
• the form becomes लेनी

Compare:

• यह दवा लेनी है। = This medicine is to be taken.
  (दवा is feminine, so लेनी)
• यह पानी पीना है। = This water is to be drunk.
  (पानी is masculine, so पीना)
• यह फल खाना है। = This fruit is to be eaten.
  (फल is masculine, so खाना)

So लेनी is not random—it matches दवा.

This is a common Hindi structure expressing obligation, instruction, or what is supposed to be done.

Pattern:

• [noun] + [verb form agreeing with noun] + है

So:

• दवा लेनी है = the medicine is to be taken
• दवा नहीं लेनी है = the medicine is not to be taken

This can sound a bit impersonal in English, which is why it is often translated as:

• You should take the medicine
• The medicine must be taken
• The medicine is to be taken

In medical or instructional language, this structure is very common.

It most naturally means something like:

• This medicine should not be taken on an empty stomach or
• You must not take this medicine on an empty stomach

The exact force depends on context. In a medical instruction, it usually sounds stronger than a casual suggestion. It is giving a rule or instruction.

It is not the same tone as a direct command like:

• यह दवा खाली पेट मत लो। = Don’t take this medicine on an empty stomach.

Your sentence sounds more like written or formal guidance, such as on a label, prescription, or doctor’s instructions.

Hindi often leaves the subject unstated when it is obvious from context.

In a sentence like this, the person is understood:

• the patient
• the listener
• whoever is using the medicine

So यह दवा खाली पेट नहीं लेनी है does not explicitly say you, but the meaning is understood as:

• You should not take this medicine on an empty stomach

This is very common in Hindi instructions.

Yes, you may hear similar versions, but they are slightly different in structure and feel.

Your sentence:

• यह दवा खाली पेट नहीं लेनी है

Another possible version:

• इस दवा को खाली पेट नहीं लेना है

Both can communicate the same idea, but the first one is very natural because लेनी agrees with दवा, and the medicine is treated as the thing to be taken.

A very common everyday version is:

• इस दवा को खाली पेट मत लेना। = Don’t take this medicine on an empty stomach.

So there are multiple natural ways to express this idea.

In standard Hindi grammar, singular this is यह and plural these is ये.

So here:

• यह दवा = this medicine

However, in everyday spoken Hindi, many speakers pronounce यह more like ये. So you may often hear:

• ये दवा खाली पेट नहीं लेनी है

Even though that sounds like the plural form to a learner, in speech it is often just a colloquial pronunciation of singular यह.

So:

• यह = standard written form
• ये = often heard in speech, even for singular

A natural pronunciation would be close to:

yeh dawā khālī peṭ nahī̃ lenī hai

A few helpful notes:

• यह is often pronounced yeh
• दवा sounds like dawaa
• खाली has a long aa sound
• नहीं often sounds like nahin or nahĩ
• लेनी has a long e sound: leni

In fast speech, the sentence may flow together quite smoothly, but the written form stays:

यह दवा खाली पेट नहीं लेनी है।

Yes, people do say it, especially in instructional contexts. It sounds very natural for:

• a doctor’s advice
• a pharmacist’s explanation
• a medicine label
• a caregiver’s instruction

It is slightly more instructional or neutral than a blunt command.

Compare:

• यह दवा खाली पेट नहीं लेनी है।
  Neutral/instructional: This medicine is not to be taken on an empty stomach.

• यह दवा खाली पेट मत लेना।
  Direct command: Don’t take this medicine on an empty stomach.

Both are natural, but your original sentence fits medical guidance especially well.