The combination of doxycycline and dairy is not inherently dangerous, but it does decrease doxycycline's effectiveness. Dairy products — milk, cheese, yogurt, and other milk-based foods — contain calcium, which interferes with the absorption of doxycycline into the bloodstream. It is recommended that patients avoid dairy products at least two hours before or after taking doxycycline. Depending on the dosage and frequency of the medication as well as the severity of the infection, the prescribing doctor may recommend not consuming dairy products at all while on doxycycline.
Doxycycline is a broad-spectrum antibiotic that can be used to treat urinary tract infections, acne, respiratory infections, and various bacterial sexually transmitted diseases. This medication works by stopping the proteins in bacteria from replicating. It is commonly prescribed because it is less expensive and has fewer side effects than other broad-spectrum antibiotics like ciprofloxacin. Unlike some antibiotics, however, it is absorbed best on an empty stomach, thus the problem of taking doxycycline and dairy together.
The decrease in effectiveness when combining doxycycline and dairy also applies to some other foods. Patients who normally take dietary supplements such as calcium, iron or a multivitamin should stop taking those while on doxycycline unless their doctor or pharmacist says otherwise. They should instead try to get these nutrients through dietary sources as much as possible during the course of treatment.
Some patients routinely eat yogurt as a probiotic while on antibiotics to maintain a healthy amount of bacteria in the body, especially in the digestive system. Doing so reduces the risk of side effects, such as upset stomach, yeast infections, or other fungal infections that are common while taking antibiotics. Since yogurt is of course a dairy product, this is not recommended while on doxycycline. Patients can instead take over-the-counter, commercially produced probiotic supplements or other non-dairy probiotic foods, such as coconut yogurt, to avoid combing doxycycline and dairy.