This study clearly documented that, within the general population, persons with CFS were significantly more likely to use medications than non-fatigued individuals. However, CFS and control subjects used similar types of drugs.
We are not aware of comparable population-based reports of medication use by people with CFS or with fatiguing illnesses. CFS-associated reports are primarily medication trials and were recently reviewed by Whiting et al . It is likely not a coincidence that of the few population reports regarding medication use in general, most describe use of pain and sleep medication since problems with pain and sleep are commonly reported to medical practitioners. However, most medications identified in this study may not reflect treatment of fatigue or other symptoms of CFS. The exceptions are medications for pain (ranked as number 1 in this study) that would influence arthralgia, myalgia, and headaches; medications for post-nasal drip associated sore throat, which might include allergy medications (#5); muscle relaxants (#10), which could influence myalgia; sleep medications (#14), which obviously would be used for sleep disturbances; benzodiazepines (#16), which could influence sleep disturbances, muscle aches, headaches, and possibly exertion-related symptoms; and CNS medications (#19), which could influence headaches, sleep disturbances, and cognitive problems associated with CFS. The drugs that were used equally by the two groups could simply reflect treatment of age-related illnesses. We are left with the unanswered question of why CFS subjects use more supplements/vitamins, hormones, antidepressants, and gastrointestinal drugs than do non-fatigued subjects or why they reported use of any drug only on one occasion.
This question highlights a major limitation of the study in regard to assignment of medication use, because we did not obtain the subject's perception concerning the problem(s) that prompted medication use. In particular, no specific questions addressed methods of combating fatigue per se. In addition, we did not address non-pharmacologic approaches to symptom relief, such as acupuncture. Since CFS patient perception of the adequacy and efficacy of medical care also affects therapy, absence of their perceptions may also influence our findings .
Comparable data for medication use in general in the United States are difficult to find. Medication use in Norway from 1988 to 1989  provides an interesting point of comparison. In our data set, pain medications were the most frequently utilized drugs, whereas in the Norwegian study they were the second most commonly used drugs by both men and women. An antibiotic was the medication most commonly used by Norwegian men and anxiolytics were the most frequently used medication in women. These differences in ranking of drug use may have little meaning because in both studies, the lists of the 10 most frequently used agents contained the same medications.
Identification of medication use patterns may also rely on identification of the symptoms or problems under therapy. As reported by Mäntyselka et al. , use of pain medications for non-acute pain is common. Another report from a study of general practice use of non-steroidal anti-inflammatory drugs (NSAIDS) in the United Kingdom found prescribing rates ranging from 220 to over 700 per 1000 patient visits . In both of these reports, the patients sought care for the primary complaint of pain. Even though pain was a common complaint, but not necessarily the primary problem in the current study, almost 90% of CFS subjects used pain medication. It is not clear why CFS subjects used more acetaminophen and central nervous system acting drugs than did the non-fatigued subjects. Medication use for pain is complex, as demonstrated by Mäntyselka et al , in that use of sedatives and anxiolytics accompanied the use of analgesics; use of these categories of drugs was also seen in our study.
Vitamin and dietary supplements constituted the second most frequently identified category of drugs used by CFS and non-fatigued subjects. These agents may be obtained directly by the individual or prescribed by a health care provider. As reviewed by Messerer et al. , supplement use in the United States population-at large ranged from 21% to 55%. In a previous analysis of vitamin/supplement use by 30 CFS subjects attending a referral clinic, 89% of patient subjects versus 40% of control subjects reported use of these agents .
Use of medications in general populations  and in the pain and supplement studies described above supports greater use by women. We determined similar overall differences between men and women in our study, but CFS- and sex-influenced odds ratios of medication use were independent. In other words, medication use by women is more common than by men and CFS is more common in women, but medication use in CFS is not dependent on the subject being female.