By Mary Kundert

Why take antibiotics long after you’re feeling fine? There’s a good reason

Q: I have some questions about antibiotics. Why do I need to continue taking an antibiotic well beyond the point when I feel fine? Why should I finish the course, as the bottle says? I’ve always believed that, when it comes to medicine, I should take the least amount necessary. The longer I take these drugs, the more likely it is that I develop intestinal problems. Wouldn’t it be better to avoid such side effects?

Liz,

Los Altos

A: It’s normal for you to not want to take medicine, especially if you feel fine. However, in the case of antibiotics, it’s very important to complete the course of therapy. If you don’t, you are adding to an already very serious problem of “antibiotic resistance.” Antibiotic resistance is what happens when microscopic, single-celled organisms called bacteria become immune to the drug that used to kill them. That drug no longer works on that type of bacteria - an increasingly common and dangerous situation.

When we have a bacterial infection, it means that our bodies are experiencing an invasion or overgrowth of bacteria. Although they are tiny, they can certainly wreak havoc when their population expands beyond the control of our immune system.

Antibiotics act to inhibit the reproduction of bacteria in different ways, because there are many types of bacteria. Antibiotics are categorized in groups or families.

These are as follows:

Aminoglycosides (e.g., Tobramycin, Neomycin)

Cephalosprins (e.g., Keflex)

Macrolides (e.g., Erythromycin, Z-Pak, etc)

Penicillins (e.g., anything with “-cillin” at the end)

Quinolones (e.g., Cipro and other “-floxacins”)

Tetracyclines (e.g., Minocin and other “-cyclines”)

Antibiotics are designed to both kill and slow the growth of bacteria at a carefully calculated rate.

If the bacteria were killed off too quickly, the toxic waste products would overwhelm our blood system, acting like a poison. To avoid this, modern medicine has designed antibiotics to be given the way you have experienced. So, although you may feel better after a few days, chances are high that your infection has only become “subclinical,” meaning that there are still many of the infecting bacteria around. The weaker bacteria were the first to go.

The stronger bacteria need to be worn down longer before they succumb to the effects of the drug. If you stop the antibiotic early, you allow the stronger ones to reproduce their strength into all the future generationsÖthereby creating antibiotic resistance.

You can limit the intestinal effects of antibiotics by taking probiotics.

Many bacteria live with us all the time, in balance with our bodies. Indeed, our normal flora of intestinal bacteria play a critical role in digestion.

When these friendly bacteria are killed off with the infecting bacteria, our gut no longer operates well. You can take probiotics at any time, though some recommend that you wait an hour after each antibiotic dose.

Kundert, who has a doctorate of pharmacology, is available by appointment only for 10-minute consultations sponsored by Los Altos Pharmacy. For an appointment call 948-1212