Assuming your personal physician will help you stockpile antibiotics for TEOTWAWKI, which should you request? Is there a logical reason to have amoxicillin on hand rather than doxycycline?
Heres what I would suggest and why.
No antibiotic is effective against every type of microbe. Certain ones will kill aerobic bacteria, others are used for anaerobic bacteria, still others are effective against resistant strains, and certain people are allergic to or intolerant of various antibiotics. The following are all generics, running about $10 for about a months treatment.
Amoxicillin is the old standby for most respiratory infections (probably most of which are viral and dont even require antibiotics). It is excellent for strep throat and some strains of pneumococcal bacteria. It is also safe for children and pregnant women. It is well-tolerated, causing little stomach distress or diarrhea. The drawbacks are that some people are truly allergic, and many bacteria have developed resistance to amoxicillin (especially staph) through overuse among both humans and animals. Anyone truly allergic to amoxicillin should substitute erythromycin or another antibiotic.
Cephalexin works on most of the same bacteria as amoxicillin, plus is stronger against Staph aureus, which mostly causes skin infections. It rarely works against MRSA (resistant staph), however. It is also well-tolerated in children and is safe in pregnant women, causing few side-effects. Like any antibiotic, it carries the risk of allergy. People who develop anaphylaxis (a life-threatening allergy) with amoxicillin probably should not take cephalexin, as there is a good 10% cross-reactivity between the two. If I had to choose between stockpiling amoxicillin or cephalexin, I would choose cephalexin. The combination drug, amoxicillin-clavulanate (Augmentin), is as strong against staph, but more expensive and harder on the stomach.
Ciprofloxacin is useful for anthrax (which Ive never seen), urinary tract and prostate infections (which are very common), and many forms of pneumonia and bronchitis. One of the more important and selective uses of ciprofloxacin is in combination with metronidazole for diverticulitis. This potentially life-threatening infection usually (or at least often) requires two antibiotics to resolve. (Levaquin and Avelox are a bit stronger than ciprofloxacin and could be substituted for this, but are much more expensive.) Ciprofloxacin is not used in women or children unless the benefit clearly outweighs the risk, although the risk of joint damage (seen in animals) appears minimal. Taking ciprofloxacin by mouth is nearly as effective as taking by IV.
Doxycycline is useful in penicillin/amoxicillin-allergic adults for respiratory infections and some urinary/prostate infections. It is avoided in children and pregnant women unless the benefit clearly outweighs the risk (of permanent tooth discoloration in children under the age of 8). Doxycycline is sometimes effective against penicillin-resistant bacteria. If I were limited to either doxycycline or erythromycin, I would choose erythromycin for stockpile.
Erythromycin is useful for most of the same infections amoxicillin is used for, and thus can be substituted in penicillin-allergic patients. However, erythromycin tends to cause the intestine to contract, often causing cramps or diarrhea. (This property is sometimes used to help patients with conditions that impair intestinal motility.) It can be safely used in children and pregnant women.