1. I have acne.

2. I have an acne.
3. I have acnes.
4. I have pimples.
5. I have pimple.
6. I have a pimple.
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Is 'acne' the same as 'pimple'?
Which ones are grammatical? Can we substitute 'pimple' for 'acne'?

1, 4, and 6 are correct.

A pimple is one blemish. Acne means a lot of such blemishes.

Acne is not a pimple acne is a whole bunch of pimples/blemishes.

1. "I have acne." - This sentence is grammatically correct and indicates that the person is experiencing multiple pimples or blemishes on their skin.

2. "I have an acne." - This sentence is not grammatically correct. The word "acne" is typically used as a plural noun to refer to multiple pimples or blemishes, so it should not be used with the indefinite article "an."

3. "I have acnes." - This sentence is not grammatically correct. Similar to the previous sentence, "acne" is used as a plural noun on its own, so it does not require the addition of an "s" to indicate plurality.

4. "I have pimples." - This sentence is grammatically correct and refers to the presence of multiple pimples.

5. "I have pimple." - This sentence is not grammatically correct. The word "pimple" is typically used as a singular noun, so it should be accompanied by an indefinite article or possessive pronoun, as shown in the next example.

6. "I have a pimple." - This sentence is grammatically correct and indicates that the person is experiencing a single pimple.

To summarize, "acne" and "pimple" are related terms that both refer to the presence of blemishes on the skin. However, "acne" is generally used to describe multiple pimples or a skin condition characterized by multiple blemishes, while "pimple" typically refers to an individual blemish.