Understanding pharmacy medicine labels

Ever received your medicines and the label reads, "Take three times a day, with food" or "Do not stop taking this medicine without consulting your doctor"? or "Do not drink alcohol while being treated with this medicine"? What do these labels mean? How much food? What would happen if I did stop taking my medicine? Surely one drink wouldn't matter? 

The labels, called Cautionary and Advisory labels, are designed to help you get the best from your medicines. Some are added to make sure that the medicine reaches your system in full strength, and others are used to help avoid nasty side effects or problems associated with suddenly stopping medicines (eg, withdrawal symptoms). The easiest way to explain them is to look at the main labels used, and explain in a little more detail about the reasons for their use.

This medicine may make you sleepy and make it dangerous to drive or operate machinery. Limit alcohol intake 

Some medicines may cause drowsiness, which could be temporary because your body may adjust to the sleepiness after a few days of taking the medicine regularly (eg, as with some antidepressants) . In some cases, the sleepiness may be deliberate (such as medicines to help you sleep) or is more likely at higher doses. If you are made drowsy by these medicines, your ability to make critical decisions, or your reaction time may be affected. This may make it dangerous for yourself and others if you drive or operate heavy machinery. Alcohol could make this effect worse, and should be avoided in this case.

Do not drink alcohol while being treated with this medicine

Sometimes medicines have unpleasant side effects or are more toxic if you drink alcohol while taking them. The most common medicine needing this label is metronidazole, an antibiotic used for infections and commonly prescribed by dentists for dental infections. This particular medicine may react with alcohol to cause a reaction similar to a severe hangover: throbbing headache, nausea and vomiting, and for this reason it is very important patients taking it do not drink alcohol for the duration of treatment, and at least 24 hours afterwards.  

Do not take indigestion remedies, iron or calcium preparations within two  hours of taking this medicine

Medicines bearing this label can be less well absorbed due to various chemical reactions, or to the stomach acid being slightly neutralised. For this reason, a gap of at least two hours should be left between taking medicines with this label and drinking milk, taking indigestion remedies or taking other medicines or supplements containing calcium or iron. It doesn't mean you need to avoid these things altogether, just don't take them at the exact same time as your medicine. 

Do not stop taking this medicine without consulting your doctor

Suddenly stopping some medicines can cause problems. Some types of blood pressure medications, for example, can cause a larger than expected rise in blood pressure if stopped suddenly, and other medicines can have withdrawal effects if stopped suddenly. Infections such as tuberculosis need to be treated for long periods of time because the cause of the problem bacterium is hardy, and can be resistant to treatment. If a patient stops treatment because they think it isn't doing anything, then it is possible the disease may return, and be unable to be treated with the usual medicines (the bacterium has become resistant). 

Take at regular intervals. Take until finished

Antibiotics usually need this label, and you should always complete the course your doctor has given you, unless he/she has specifically told you otherwise. This will reduce the risk of the infection returning, or the treatment not being effective. By taking them at regular intervals, you will ensure that an even amount is in your system. If your prescription says to take them three times a day, then you would be best to take them every eight hours; four times a day would be best taken six hourly. If you can't manage the exact eight (or six) hours, then try to take them as close to this as you can, it will mean they are more effective. 

Take with or after food

You don't have to eat an entire meal before taking your medicine if this appears on your label - usually a small amount of food will be enough. It may be that this medicine could upset your stomach, or not be absorbed properly if you have an empty stomach when you take it. 

Take each dose on an empty stomach - one hour before or two hours after food

Some medicines need to be taken on an empty stomach because they won't be absorbed properly if your stomach is full.

If your medicine label has something on it that you don't understand, ask your pharmacist or doctor. They will be happy to explain it to you.

For a pdf version of this health topic click here.

Original material provided by Pauline Hamilton, Dip. Pharm, MRPSGB. Reviewed by everybody, March 2006.