While administering the NHIS, interviewers showed respondents a flash card containing a list of herbs and asked, "During the past 12 months, have you taken any herbal supplements listed on this card for yourself?" Respondents who answered affirmatively (i.e., a "Yes" response in HERYR) were asked, "During the past 30 days, did you take any of these herbal supplements?" Sample adults who answered that question affirmatively (i.e., a "Yes" response in HERMO) were instructed, "Please tell me which of these supplements you took in the past 30 days. If you take more than one herb in a single supplement, select 'combination herb pill.'" Interviewers were told to "enter all that apply." Sample adults who selected "combination herb pill" (HERMOCOMBO) were asked how many combination herb pills they had taken (HERCOMBONO) and which herbs were included in the first combination herb pill.

Evening primrose was one of 45 possible specific herbs that respondents could indicate taking as part of their first herbal supplement containing more than one herb. The other such herbs recognized by the NHIS are:

• androstenedione (HER1COMAND)

• Prebiotics or probiotics (HER1COMBIOT)

• Carnitine (HER1COMCARN)

• Chasteberry (HER1COMCHAS)

• Chondroitin (HER1COMCHON)

• Conjugated Linolenic Acid (CLA) (HER1COMCLA)

• Coenzyme Q-10 (HER1COMCOEN)

• Black cohosh (HER1COMCOH)

• Comfrey (HER1COMCOMF)

• Cranberry (pills, gelcaps) (HER1COMCRA)

• Creatine (HER1COMCREA)

• DHEA (HER1COMDHEA)

• Echinacea (HER1COMECH)

• EGCG (pills) (HER1COMEGCG)

• Ephedra (HER1COMEPH)

• Feverfew (HER1COMFEV)

• Fiber or psyllium (pills or powder) (HER1COMFIB)

• Fish oil, Omega 3, or DHA (HER1COMFISH)

• Flaxseed oil or pills (HER1COMFLAX)

• Garlic supplements (pills, gelcaps) (HER1COMGAR)

• Ginseng (HER1COMGIA)

• Ginger pills or gelcaps (HER1COMGIG)

• Ginkgo biloba (HER1COMGIK)

• Glucosamine (HER1COMGLUC)

• Goldenseal (HER1COMGOLD)

• Grape seed extract (HER1COMGRA)

• Green tea pills (not brewed tea) (HER1COMGTEA)

• Guarana (HER1COMGUAR)

• Hawthorn (HER1COMHAW)

• Horny goat weed (HER1COMHORN)

• St. John's wort (HER1COMJOH)

• Kava kava (HER1COMKAV)

• Lecithin (HER1COMLEC)

• Lutein (HER1COMLUT)

• Lycopene (HER1COMLYCO)

• Melatonin (HER1COMMEL)

• Milk thistle (HER1COMMIL)

• MSM (HER1COMMSM)

• SAM-e (HER1COMSAM)

• Saw palmetto (HER1COMSAW)

• Senna (HER1COMSEN)

• Soy supplement or isoflavones (HER1COMSOY)

• Valerian (HER1COMVAL)

• Other (HER1COMOTH)

Sample adults taking a second combination herb pill were also asked which herbs were included in that combination pill. See HER2COMEVE for respondents whose second combination herb pill included Evening primrose.

Both sample adults and respondents for sample children could report use of any of the above-mentioned herbs as a supplement on its own, rather than as part of a combination pill. See HERMOEVE for persons who took a separate Evening primrose supplement.

The summary variable HER1MOST reports the first herbal supplement taken most often by sample adults and sample children during the past month. For more information about the full range of variables related to the use of herbal supplements, see HERMO.