Antibiotics are among the most commonly-prescribed drugs and one of the most important medical achievements of the 20th century.
Comprised of more than 80 different antibacterial agents, they are used to treat and prevent bacterial infections, including inflammation of the lungs, bladder and tonsils.
But bacteria can become resistant to antibiotics.
This can occur if you take them when you don’t need them, the dosage is too high or the duration of intake is too long.
What’s more, the interaction of some antibiotics with certain medications and foods can have undesired effects, and possibly serious consequences.
The following are problematic:
If you’re ill enough to require medication, you shouldn’t drink alcohol, no matter what you’re taking, because the interaction could be dangerous, warns Dr Thomas Loescher, an infectious and tropical disease specialist, and member of the Professional Association of German Internists (BDI).
Alcohol can increase or reduce the effect of medications, while medications can increase the effect of alcohol.
Antibiotics are no exception.
“In combination with alcohol, the antibiotic metronidazole, which is prescribed for illnesses that include vaginal and intestinal infections, causes pronounced symptoms of intolerance such as headache, nausea and vomiting,” he says.
Milk and other dairy products typically disrupt the metabolism of medications, mainly because of the presence of calcium.
“(Calcium) diminishes the effect of many medications”, particularly antibiotics, notes Ursula Sellerberg, spokeswoman for Germany’s Federal Chamber of Pharmacists (BAK).
“Some antibacterial agents bind with calcium in the intestines to form molecular complexes so stable that they can’t pass through the intestinal wall” and enter the bloodstream, she explains.
As a result, the medications aren’t metabolised and the active substance is excreted without having any effect.
This occurs chiefly with antibiotics such as tetracycline and fluoroquinolones.
She advises avoiding dairy products for two hours before and after taking the medications.
Whether carbonated or not, mineral water isn’t suitable for washing down certain medications, Sellerberg warns.
The reason is that it contains many minerals such as calcium, iron and magnesium.
Like the calcium in milk, the minerals can bind with the active substances of the antibiotic to form stable complexes, thereby rendering the medication ineffective.
You should therefore avoid drinking mineral water for two hours before and after taking an antibiotic.
“You’re always on the safe side if you take an antibiotic with a large glass of tap water,” she says.
“Large” in this case meaning 250-300ml.
These too should be avoided before you take an antibiotic.
Dr Loescher warns against grapefruit juice in particular.
“It contains certain enzyme inhibitors that can disrupt the metabolism of some medications in the intestines and liver.”
The effect of stimulating beverages such as coffee, black and green tea, cola, energy drinks and brews from guarana or mate, can be intensified by taking certain antibiotics, possibly resulting in a rapid heartbeat and difficulty sleeping.
Finally, when is the best time to take an antibiotic: before, during or after a meal?
There’s no general rule, according to Sellerberg.
Ampicillin, for example, should be taken on an empty stomach – 30 to 60 minutes before a meal, in other words.
Minocycline should be taken during a milk-free meal, and cefuroxime axetil after a large meal.
So you should always consult your doctor or a pharmacist on the proper time to take a prescribed antibiotic. – dpa