Bismuth subsalicylate (Pepto-Bismol)
may be used for prophylaxis but should not be used for more than 3 weeks. It can also be used after the onset of symptoms to reduce their duration.
(1) The standard dose is 2 tablets or 2 ounces QID.
(2) Side effects include blackening of the tongue and stools, constipation and ringing in the ears.
(3) It should not be used in patients with aspirin allergy, renal insufficiency, or gout.
(4) It should not be used for patients taking oral anticoagulants, probenecid or methotrexate. It may interfere with absorption of doxycycline, which is sometimes used for malaria prophylaxis.
(5) It should be used only with care in children and pregnant women.
Antidiarrheal agents
may decrease the number of diarrheal stools after onset of symptoms.
(1) Antidiarrheal agents include
diphenoxylate
HCl with atropine sulfate (Lomotil) and
loperamide
HCl (Imodium).
(2) These agents can cause problems in some patients with serious infections. They should not be used in patients with possible dysentery (when there is blood or mucous in the stools).
Antibiotics
are in general not recommended for routine prophylaxis since not all travelers develop travelers diarrhea. In addition, antibiotics may have adverse side effects.
(1)
Fluoroquinolones
are effective for prevention or treatment in many parts of the world, but resistance is an increasing problem. They should not be used in pregnant women or children under 18 years of age.
(2)
Trimethoprim-sulfamethoxazole
may be used in children and other patients unable to take fluoroquinolones, but resistance is an increasing problem.
(3)
Rifaximin
is a nonabsorbed oral antibiotic that is effective for noninvasive strains of E.coli in adolescents and adults. It should not be given in pregnant women, in children or for treatment of infections with blood or mucous in the stool (presumptive evidence of an invasive organism).
(4)
Azithromycin
with or without loperamide can be used in pregnant women and children. It can be used in someone traveling to a region where fluoroquinolone resistance is high or in someone who has not responded to a fluoroquinolone.
(5) Other agents may be needed depending on the patient, the etiologic agent, and local antibiotic resistance patterns.
(6) Many of the antibiotics commonly used are contraindicated during pregnancy.
(7) Antibiotics may be started promptly after the onset of symptoms, although sometimes patients are advised to wait until they have passed a third unformed stool.
(8) The use of antibiotics for prophylaxis may be considered in:
(8a) a traveler with pressing needs who cannot afford to be ill even for a moment
(8b) a traveler with one or more risk factors for complications.
