Calcium is the most abundant mineral in your body. It is needed to keep your bones and teeth healthy. Calcium also helps the heart, nerves, and muscles work well. To properly absorb and use calcium in your body, you need several other nutrients, including magnesium, phosphorous, and especially vitamin D and vitamin K. The best way to get calcium is through the food you eat. Calcium is found naturally in dairy products (e.g., milk, cheese) and is added to some drinks (e.g., orange juice, soy milk). But some people may need to take calcium supplements to get the recommended amount, especially older people as they start to lose bone with age.
Calcium supplements are available in the form of calcium carbonate (e.g., Tums) or calcium citrate (e.g., Calcitrate), or as part of other health supplements, such as multivitamins. Unfortunately, calcium supplements interact with some medicines when they are taken at the same time. When this happens, it can often increase or decrease the amount of medicine that your body absorbs. Sometimes, it works the other way around and the medicine changes how much calcium your body absorbs. So, either the calcium supplement or the medicine does not work very well. Here is one example of an interaction when taking a calcium supplement at the same time as a certain antibiotic, leading to ineffective treatment of a serious infection.
A consumer with diabetes received prescriptions for two antibiotics to treat a serious foot infection. One of these antibiotics was ciprofloxacin (Cipro). When ciprofloxacin and a calcium supplement are taken at the same time, the ciprofloxacin is not absorbed properly, making it so the antibiotic cannot treat the infection. When the consumer filled the antibiotic prescriptions at his local pharmacy, the pharmacist did not tell him to take the ciprofloxacin at least 2 hours before or 6 hours after taking his calcium supplement to avoid an interaction. Also, the pharmacy label on his medicine vial did not warn him to do this. Because he took his ciprofloxacin at the same time as his calcium supplement, the antibiotic could not work and his foot infection was not properly treated.
Calcium supplements are usually safe to take, but you need to consider what else you are taking—and it is not just ciprofloxacin that is a problem. This is not a complete list, but the following are just a few examples of the types of medicines that may interact with calcium supplements and should be taken a few hours apart:
Antibiotics: Calcium supplements can decrease the absorption of certain antibiotics, including tetracycline, ciprofloxacin, levofloxacin, and norfloxacin. Taking these antibiotics at least 2 hours before or 6 hours after the calcium supplement should help, but again, speak with your healthcare provider for specific instructions.
Osteoporosis medicines: Taking calcium supplements and bisphosphonates (used to treat osteoporosis [weak bones]) at the same time may decrease the absorption of the osteoporosis medicines. Bisphosphonates include alendronate (Fosamax, Binosto), ibandronate (Boniva), and risedronate (Actonel, Atelvia). Calcium supplements should be taken at least 30 to 60 minutes after the osteoporosis medicine.
Anti-seizure medicines: Medicines used to control seizures, such as phenytoin (Dilantin), carbamazepine (Carbatrol, Equetro, Tegretol, Epitol), phenobarbital, and primidone (Mysoline), may lower your calcium levels or the levels of anti-seizure medicines. They need to be taken at least 2 hours before or after calcium supplements.
Here’s what you can do: It is very important to talk to your pharmacist or another healthcare provider about taking calcium supplements (or any other dietary supplement), especially if you have any health conditions or are taking other medicines, including over-the-counter (OTC) medicines. Also consider the following tips to avoid interactions between dietary supplements and medicines:
• Keep your medicine list updated with all prescription and OTC medicines, dietary supplements, and herbal products. Be sure to include any vitamins and minerals that you take, such as calcium. Show this list to your pharmacist and every other healthcare provider, especially before starting a new medicine.
• Talk to your pharmacist about any new medicines you start. Ask if there are any foods, drinks, dietary supplements, herbals, or other products that you should avoid.
• When buying a dietary supplement, including calcium supplements, always ask the pharmacist whether it is safe to take with your current medicines.
• Really, this is so important that it bears repeating: Talk to your pharmacist or another healthcare provider about any dietary supplements you take.