Rehydration saves more people from diarrhoea than any tablet, and loperamide, antihistamines, albuterol inhalers and prednisone are useful extras that each have a case where they are the wrong choice: loperamide is not for bloody diarrhoea or high fever, antihistamines do not treat a severe allergic reaction, and prednisone is a powerful drug that can worsen an uncontrolled infection. No amounts are given here.
Part of Critical Drugs to Prioritize
Diarrhoea and asthma are common and can become emergencies, and the drugs for them have conditions in which they are the wrong choice.
Fluid Replacement Comes Before Any Tablet
Diarrhoea kills mainly through dehydration, especially in children. Replacing fluid and salts is the treatment; a drug that slows the gut is secondary. Home sugar-and-salt rehydration mixes exist, but the proportions matter and sources differ, so follow the method in Dehydration Treatment and do not add extra salt to be safe: too much is harmful. This article does not give a recipe.
The Drugs
- Loperamide (Imodium). Slows diarrhoea. It is light, stable and cheap. It is not for diarrhoea with blood or with a high fever, and it is a second step after fluids.
- Diphenhydramine (Benadryl). An antihistamine for allergy, also used for sleep and nausea. It causes drowsiness and adds to alcohol, opioids and other sedatives. It does not treat anaphylaxis; epinephrine does (see Critical Specialty Medications).
- Albuterol inhalers. Open the airways in asthma and similar breathing trouble. An asthmatic without an inhaler can die in a severe attack. Inhalers lose propellant over time, so a weak or sputtering puff or an empty dose counter means the canister is nearly spent. An attack that does not ease with the inhaler is an emergency.
- Prednisone. A corticosteroid that reduces severe inflammation, used in allergic reactions, asthma flares and some other conditions. It is powerful: it can worsen an uncontrolled infection, raise blood sugar and, after longer use, should not be stopped suddenly. Short courses carry fewer risks than long ones.
Method: Using These Safely
Step 1: Treat fluid loss first. Small, frequent sips of a proper rehydration drink.
Step 2: Check the red flags. Blood in the stool, high fever, severe abdominal pain, or signs of severe dehydration need more than loperamide.
Step 3: Match the drug to the problem. Breathing trouble with swelling of the face or throat is anaphylaxis, not an antihistamine case.
Step 4: Take amounts and limits from a reference. They are not given here.
Common Mistakes
- Stopping diarrhoea before replacing fluid. The body is clearing something, and the loss of fluid is the danger.
- Using an antihistamine for a severe reaction. It is too slow and too weak.
- Giving prednisone for any infection that is not understood. It can make things worse.
Safety
Breathing trouble and dehydration are emergencies, and the wrong drug can delay the right one
Struggling to breathe, blue lips, swelling of the throat, or a person who cannot keep fluids down needs urgent help beyond this list. Do not give sedating antihistamines to a person who is struggling to breathe. Do not guess an amount for any drug here.
What’s Next
- Learn next: Storage to Extend Medication Life — keeping what you have collected
- Combine with: Dehydration Treatment — the core treatment for diarrhoea