I was surprised to learn that lactose is present in many medications, despite the fact that 30 to 50 million Americans are allergic to the milk sugar. Since lactose is slightly sweet, water soluble and non-reactive, it is a common filler in prescription and over-the-counter drugs .

Lactose intolerance is a person’s inability to digest milk sugar due to a deficiency of the lactase enzyme. Not to be confused with a milk allergy, which is one’s inability to digest milk proteins, it causes abdominal pain, bloating, gas, diarrhea and nausea . Although being lactose intolerant is not life threatening, the symptoms can be severe. The main treatment for lactose intolerance is diet modification and/or taking over-the-counter medications that contain the lactase enzyme.

Lactose is present in more than 20% of prescription drugs and about 6% of over-the-counter medication, especially in birth control pills and ironically those that treat stomach acid and gas. Compared to milk and foods measured in grams, medications contain small amounts of lactose measured in milligrams, which is why most pharmacists claim that no or an extremely small reaction will occur. But, an article co-authored by five pharmacists claims that although reports are rare, medications containing lactose can cause symptoms and hinder the effectiveness of the medication.

Due to the lack of labeling of lactose quantity, the consumer is usually unable to detect the milk sugar without further research. Since lactose amounts can vary by lot and manufacturers, the five Pharmacists claim that one cannot make a list of lactose-free medications. But, a lactose-intolerant blogger posted a list of lactose-free birth control pills (and injections) on his site after consulting with a pharmacist and the Information Centre at the Royal Pharmaceutical Society of Great Britain has issued a list of lactose-free medications .

I hope this is some added relief for those who suffer from lactose intolerance and please make sure to research and read the label and instructions for any medications you are planning to take. After all, to quote Nobel Prize winning biochemist Martin H. Fischer, “Half the modern drugs could well be thrown out the window, except the birds might eat them.”