The Food and Drug Administration said yesterday it will soon start requiring druggists to warn women who take birth-control pills that smoking greatly increases their chances of suffering heart attacks or strokes.

The agency will require druggists to issue such warnings whenever they fill a prescription for oral contraceptives. Doctors and clinics will have to do the same when they dispense the drugs.

An estimated 2.4 million to 4 million American women take the pill and smoke. For them, Commissioner Donald Kennedy told a press conference, "the new FDA message is both loud and clear: if you take the pill, don't smoke; if you must smoke, find another method of contraception."

An agency-ordered label that manufacturers must provide to pharmacists for distribution starting April 3 includes a special boxed warning that the risk from cigarette smoking "increases with age. . . and is quite marked in women over 35."

Drawing on published studies, the label says that the risk of a heart attack in a pill user who smokes is generally about five times higher than in a user who doesn't and 10 times higher than in a nonuser/nonsmoker.

For a fatal heart attack, the FDA estimates the annual risk as: user/smoker, 1 in 10,000 in the 30-39 age group, 1 in 1,700 in the 40-44 group; user/nonsmoker, 1 in 50,000 in the 30-39 group, 1 in 10,000 in the 40-44 group; nonuser nonsmoker, 1 in 100,000 in the 30-39 group, 1 in 14,000 in the 40-44 group.

"Heavy smoking (about 15 or more cigarettes a day) further increases the risk," the label reads. "If you do not smoke and have none of the other heart attack risk factors [high blood pressure, high cholesterol, obesity and diabetes], you will have a smaller risk than listed. If you have several heart attack risk factors, the risk may be considerably greater than listed."

Smoking aude, a reporter asked the commissioner what advice would he give his wife or a daughter if either asked whether to take the pill? Kennedy noted that he is not a physician, but said that his advice would be "to find another method."

Currently, an estimated 8 million to 10 million women in this country and 40 million elsewhere - all of them healthy - take the pill. Did the commissioner know of a drug widely prescribed for sick people that was as "talented" in producing diverse diseases? After a long pause Kennedy told the questioner that this was "not a game I've tried." He had no drug to nominate.

The pill label has been in preparation for almost three years and will be distributed with a separate, easy-to-read summary. The label will replace an admittedly inadequate patient leaflet that was based on 1968 data and hasn't been changed in eight years to incorporate a virtually unrelieved flow of adverse scientific reports about the pill.

The FDA published a draft label in December, 1976. It then solicited and evaluated comments before issuing the final version yesterday.

A few manufacturers won't have to supply the final version until Aug. 3, because they accepted an FDA offer of a four-month postponement in exchange for immediate distribution of the 1976 draft.

Some highlights of the final version:

A comparison of effectiveness of various contraceptive methods (pills combining estrogen and progestogen, the female hormones, are rated at about 99 percent).

A chart comparing death rates with the same methods, and with no method.

A listing of women who shouldn't take the pill (because of conditions such as leg or lung clots, known or suspected cancer of the breast or sex organs, and unusual, undiagnosed vaginal bleeding).

Singals of possible serious adverse effects that require contacting a doctor (including sharp pain in the chest, calf or abdomen, and sudden severe headache, vomiting, dizziness, partial or complete loss of vision or mental depression).

A statement on whether the pill causes cancer. Animal findings "suggest" it may, but studies in women now using it "have not confirmed" the possibility."

In 1966 the chairman of a panel of outside experts said that a relatively mild report on the then-known hazards of the pill was "a yellow light of caution." Asked about the deluge of adverse new information since them, Kennedy said that "the light is still amber."