I am not sure which article to use in the following context:
- She has been suffering from a headache.
- She has been suffering from the headache.
Please clear up my doubt.
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Peter Shor hit on something very pertinent in his comment to Barrie England; when discussing maladies, sometimes English uses the, sometimes a, and sometimes no article at all:
Andy caught the flu.
Fred had a headache.
Fran has arthritis.
Sure, the variants abound:
Candy had measles last summer.
I would think that, in the context provided by the O.P.:
would be more common than:
but that doesn't mean the article the would never be used:
(although, in that last example, I'd might be more apt to use alleviate headache pain, depending on the context).
In sentences such as your examples, The headache was used in the past, but it's now ususal to speak of a headache.
J.R provides a great list of examples of article use in various diseases and conditions. His examples seem to suggest a vague pattern.
Chronic diseases and conditions - (arthritis, thyroid cancer, depression) usually take no article. They are not discrete but an ongoing state. Simiarly, tuberculosis, Lyme disease. There are exceptions. I have heart disease. However, I have a heart condition.
Diseases and conditions that you get many times - (headache, backache, cold) often are preceded by a when you aren't trying to distinguish this bout from a different episode. I had a cold last winter; but The cold I had last winter was a killer. There are numerous exceptions. I had the flu and I suffered from hay fever all summer.
Diseases and conditions that you get only once - (mumps, measles) when these take an article, often take the. But they sometimes do not take an article (chicken pox, rubella). And they may take a if proceeded by bout. I had a bout of measles.
"The" refers to a specific headache while "a" is any headache. If the writer has already mentioned the subject as having a headache, then use "the" to show it is the same headache and "a" if it is a new one. If it is the first mention, use "a."
In English, the definite article is used to refer to a specific, individual object. So to use the, the thing referred to must be already known to the listener/reader or have been identified in a previous sentence or be identified specifically in the same sentence.
Here's one I couldn't resist, sorry...
To use the definite article to refer to an unidentified object is to create for the listener/reader an expectation of significance yet to be explained. This can be used for powerful literary effect....
or, in a third person narrative, can simply indicate that the object is familiar to the protagonist (and is too commonplace to require explanation).
Anyway, to answer your question directly; "a headache" is the appropriate article in your example unless she regularly has a particular kind of headache in particular circumstances and this is known to the person with whom you are communicating.
Well, this is a good example of why learning English as a second language is difficult.
'She has a headache' is the normal way to speak, and 'She has the headache' would be used only to compare, if there is someone else who might have a headache. Otherwise, 'the headache' would definitely be a mistake, and point to the speaker as likely coming from European languages such as French which emphasize the definite article.
J.R. has a good set of examples, so maybe we can understand a little as to why these may occur — thus to try to put a little sense into a language mixed from others.
These are indeed anecdotal and opinions, but based on having lived in the U.S., Britain, and Europe each for considerable time.