Whether it’s prescription medication, painkillers or vitamins, many of us regularly pop pills. But if taken at the wrong time, or in the wrong combination, they can cause unexpected – and sometimes dangerous – results.
“Just because something can be bought over the counter, doesn’t mean it’s safe to combine with other prescriptions,” says pharmacist Thorrun Govind, former chair of the Royal Pharmaceutical Society. If you want to start taking something new – even herbal supplements – seek advice or you could do yourself some harm.”
ACTIVATED CHARCOAL AND CONTRACEPTION: Activated charcoal is popular with detoxers, with fans claiming it can cleanse toxins, beat bloating and cure a hangover. “It’s become a trendy ingredient sold in tablet and powder form and people think they can help detox, but your body does this naturally and doesn’t need any help,” says Govind. But it’s not just the waste of money that is an issue. You could end up with an unplanned pregnancy if you don’t use it wisely.
“Charcoal is used in hospitals to treat poisoning or overdoses by absorbing chemicals in the stomach,” she explains. “But it can also impact your antidepressants and birth control, reducing how much of the medication the body absorbs and decreasing their effect, so it is best avoided.” However, it’s not the only supplement that could cause major issues with the medication your doctor has prescribled.
Here are three other problematic combinations that you should also be aware of:
EVENING PRIMROSE AND BLOOD THINNERS: Evening primrose oil has long been taken by women to relieve symptoms of PMT. Its active substance – gamma-linolenic acid (GLA), an omega-6 fatty acid found in plant oils – is a potent anti-inflammatory thought to help ease acne, hot flushes and breast tenderness.
But there’s a downside. “Evening primrose oil can potentially interact with blood thinners such as warfarin, increasing the risk of bleeding,” says Govind. “You shouldn’t take it if you have a bleeding disorder or are about to undergo a procedure. If you experience unusual bleeding, bruising or dark stools seek medical attention.”
CALCIUM AND ANTIBIOTICS: Taking calcium, which is sometimes recommended for older women who are at risk of osteoporosis, could stop your antibiotics from working. “Calcium can decrease the absorption of other drugs, particularly tetracycline antibiotics,” says Govind. These broad-spectrum antibiotics are used to treat chest and dental infections and rosacea.
Govind recommends always leaving at least three hours between taking the two. “Similarly, oral zinc supplements are thought to reduce the efficiency of tetracyclines, so leave between two and three hours between taking zinc and antibiotics too,” she adds.
ST JOHN’S WORT AND ANTIDEPRESSANTS: It’s seen as an over-the-counter solution to low mood, a natural antidepressant that’s available in local health food shops. But taking St John’s wort is fraught with potential problems. “It has significant interactions with quite a lot of other medications,” warns Govind.
St John’s wort can reduce the effect of some statins and decrease the efficiency of contraception, particularly desogestrel, the progesterone-only mini pill. “It also decreases the concentration of digoxin, which is used to treat heart conditions by making the heart beat more strongly.”
And it can become extremely dangerous when taken on top of prescription SSRI antidepressants such as citalopram, which work by boosting the amount of the neurotransmitter serotonin in the brain. “It can increase the risk of serotonin syndrome, which occurs when the levels of serotonin in the brain become too high,” she adds. “Symptoms include diarrhoea, rigidity and seizures, so it is potentially life-threatening.”
