When it comes to health risks, sex does matter.

Women are twice as likely to get multiple sclerosis, rheumatoid arthritis, and migraines.

Those gender differences extend to the medicine cabinet in ways many people are not aware.

Robert Davis and Joanne Mergaux share a lot in life.   They love the water, walking on the treadmill and reading books.  They are father and daughter.

"And now we share high blood pressure," said Mergaux, who says her blood pressure is normally 165 over 105.

Davis' digits are 169/108.

Despite their genetic connection, they cannot take the same medication.   Davis takes Coreg.  His daughter is on Verapamil.

Why?

Liver enzymes unique to a woman's body help Verapamil effectively reduce her high blood pressure.

But Dr. John Osborne would never prescribe it to Joanne's father.  

"Sometimes, what's good for the goose is not good for the gander as far as medications go," says Dr. Osborne.  "Or sometimes side-effects or drug interactions make us want to use one kind of drug instead of another."

For years, drugs were only studied in men.   But these days, scientists are beginning to recognize basic physiological differences between men and women also influence their reactions to drugs."

For example, scientists know ibuprofen is less effective at pain relief in women than men.

Anti-depressants are absorbed differently in the female body -- and may require more dosage adjustments.

Diazepam, a common muscle relaxant -- impairs a woman's motor skills more than a man's.

And, Viagra -- which restores blood flow to a male's nether-region to improve sexual performance -- does not have the same benefit for his partner.

"One size fits all? We don't buy it in this pharmacy,” said Jim Porter, of Pharmacy Compounding Specialties in Dallas.  He and other pharmacists there have been concocting individualized drugs for years.

"We're looking at body weight, of course. We're looking for male, female, age," says Porter.

They also take into account metabolism and hormones, which can negate the effects of antibiotics in women.

Acetaminophen can also lose its effectiveness in a woman taking birth control.

"We see these things now where we didn't before," says Porter.  "We just thought for the men, well, it didn't work, so let's try another."

Scientists don't yet understand all the reasons for gender differences in medications.

But it does add another dimension to treatment.

"At least if I know I have some idea what medications are generally going to work better in men than women," said Dr. Osborne, "I already have figured that into the equation and it avoids a lot of trial and error."

E-mail jstjames@wfaa.com