Introduction

Are you going somewhere exciting? For business or pleasure? Nearly 40%-60% of travellers experience the most common travel-associated illness- traveller’s diarrhoea (TD).¹

This short article serves as a source of instant information related to TD - what it is, the main symptoms, how to relieve those symptoms, and what over-the-counter (OTC) medications to look out for.

Here are three key takeaways:

• Preventing dehydration by fluid replenishment is priority when suffering from TD
• OTC medications for TD makes stools less watery and loose, but can also trap the germ responsible for the infection in your body
• Anybody who is pregnant, breastfeeding, or has liver or kidney problems should seek advice from their doctors or qualified medical professional before taking the OTC drugs mentioned in this article

What is Traveller’s Diarrhoea (TD)?

TD is when you have had three or more loose stools in a day, it is an acute form of diarrhea. 

It is common to experience TD in warmer places without proper refrigeration or hygiene measures, the heat may cause germs like bacteria, viruses and parasites to grow in food and water,thus increasing the chances of being infected with them. 

What happens in the human body when suffering from TD?

When contaminated food or drink is consumed, viruses and bacteria can grow from 6 - 24 hours in the intestines, until symptoms occur. Parasites may take 1 to 3 weeks.¹ These germs reduce the amount of water and nutrients that are absorbed by the body. This causes the production of more feces at a quicker rate, resulting in increased bowel movements and watery stools.¹

What are the main symptoms of TD?

• Diarrhea (more than three loose stools in a day)
• Stomachaches
• Fever
• Nausea
• Vomiting

The symptoms of TD cause dehydration; therefore, replenishing fluids and electrolytes is extremely important. Electrolytes come from salts and are vital for maintaining and restoring normal intestinal function, namely absorption of water and nutrients. An oral rehydration solution is an easy and excellent way to address these symptoms, and can be made with household ingredients. Recipes can be found here. While TD usually resolves itself in 3 - 5 days,² if symptoms continue and worsen, seek medical attention. 

What are the commonly available OTC drugs for TD? 

There are OTC drugs which are available internationally. However, they are only beneficial in the short term for travellers who cannot afford to experience diarrhoea during trips. OTC medications for 

TD can trap the germs in the body, prolonging the infection and making it worse.³ The priority when one suffers from TD is still replenishing fluids to prevent dehydration. 

That being said, these accessible OTC drugs are called:

• Loperamide
• Bismuth subsalicylate
• Diphenoxylate (and atropine)

Loperamide, bismuth subsalicylate, and diphenoxylate (and atropine) are three types of antidiarrhoeals. Bismuth subsalicylate is also an antacid.^4,5,6,7

Antidiarrheals alleviate the symptoms of diarrhoea when one is suffering from gastrointestinal infections like TD. When one experiences TD, stomach acid levels may be higher than normal, causing discomfort. Antacids counteract the amount of stomach acid by a chemical process called neutralisation.

Stopping diarrhoea during a stomach or intestinal infection is very important, as it can cause excessive water loss due to the body’s natural defence mechanism of trying to get rid of the germ responsible for the infection. In addition to excessive water loss during diarrhoea, the body also loses electrolytes. Electrolytes, such as sodium and potassium, are found in water and food, and these electrolytes play a significant role in maintaining hydration in human bodies. OTC antidiarrhoeals prevent excessive dehydration and loss of electrolytes.

An overview of how each of these drugs works

Loperamide works by slowing down the contractions or movement of your intestinal muscles, also called intestinal motility. By decreasing the intestinal movement in your body, it gives your intestines more time to absorb water and electrolytes.⁴ This makes your stool less loose and more solid, ultimately reducing the frequency you go to the toilet. 

Bismuth subsalicylate is an antidiarrheal and an antacid.⁵ When one takes bismuth subsalicylate, the medication itself separates into two parts: bismuth and subsalicylate. The bismuth part of the medication relieves discomfort by neutralising the amount of stomach acid.⁵ In addition, bismuth coats and protects the stomach lining, reducing irritation caused by excess stomach acid.⁵ The subsalicylate part of this medication provides antidiarrheal effects by slowing down the release of water into the intestines,⁵ which causes watery stools in the first place. Subsalicylate also reduces intestinal inflammation,⁵ further reducing excessive water loss by watery stool. 

Diphenoxylate is an antidiarrheal medication which works in a similar way as Loperamide, they both relieve the symptom of diarrhea by slowing down intestinal movement,^4,6 ensuring more time for water and electrolyte to be absorbed by the intestines. Resulting in more solid stool. Diphenoxylate is commonly taken with another medication called atropine for safety reasons.^6,7

Common brand names of Loperamide, bismuth subsalicylate, diphenoxylate and atropine

These OTC medications are internationally available. Here are some common brand names.^4,5,6

FAQs

How are these medications normally taken?

Loperamide, bismuth subsalicylate, and diphenoxylate are all taken by mouth.^8,9,10

Loperamide can come in the form of a tablet, capsule or a lyophilisate. An oral lyophilisate will instantly dissolve once it comes in contact with your tongue, there’s no need to have water with it.

Bismuth subsalicylate can be taken by mouth as a chewable tablet or as an oral suspension.⁹

Diphenoxylate and atropine can be taken orally as a tablet or as a liquid solution.¹⁰

Is it safe to take any of these medications if I have kidney or liver problems?

Loperamide is safe to take if you have kidney problems, but if you have liver problems, please take it with caution.¹¹

Bismuth subsalicylate should not be used by patients with kidney or liver problems.³

Diphenoxylate and atropine should be taken carefully by patients with kidney or liver problems.¹²

The best practice is to check with your doctor or a qualified medical professional before traveling. 

Is it safe to take any of the medications mentioned in this article if I am pregnant?

There is not enough information or data to suggest if it is safe to take loperamide when pregnant.¹³ Therefore, the best advice from medical professionals is to avoid it.

The National Health Service (NHS) has strongly suggested not to take bismuth subsalicylate as it may affect the baby, especially after 30 weeks of pregnancy.¹⁴

diphenoxylate and atropine should only be taken if the benefits outweigh the risk to the baby,¹⁵ even though there isn’t enough information to suggest harm to the baby. 

Is it safe to take any of the medications mentioned in this article if I am breastfeeding?

Loperamide can be taken if you are breastfeeding. This is because only tiny amounts of it can be found in breastmilk, and this amount is too small to be harmful to the baby.⁸ It is always safer to consult with a GP. 

Bismuth subsalicylate should not be taken if you are breastfeeding.⁹

Diphenoxylate and atropine should not be taken if you are breastfeeding. This is because atropine and diphenoxylate can be found in the breast milk and babies who are breastfed may experience side effects of this medication.¹⁵

Is it safe for children to take any of the medications mentioned in this article?

Loperamide can be taken by children aged from 4 to 17 years.⁸ Full description of dose and how long to take it for can be found here. 

Bismuth subsalicylate should not be taken by children younger than 12 years of age.⁹

Diphenoxylate and atropine should not be given to children aged younger than 6 years due to risk of respiratory complications. It is safe for children aged between 13 and 17 years. In addition, only the liquid solution should be given to children of the appropriate age range.¹²

Side effects of loperamide, bismuth salicylate, and diphenoxylate and atropine

Loperamide may cause headache, nausea and gastrointestinal disorders. A list of potential side effects caused by loperamide can be found here.

Bismuth salicylate can make your tongue and stool black. This is temporary and harmless, and is the result of a reaction between the bismuth and certain chemicals in your mouth and intestines. A list of potential side effects caused by bismuth salicylate can be found here.

Diphenoxylate and atropine can cause gastrointestinal disorders, especially if you have ulcerative colitis. A list of potential side effects caused by diphenoxylate and atropine can be found here. 

Are there any foods or drugs I should avoid when taking these medications to avoid side effects?

An interaction is a reaction which happens between two drugs (drug-drug interaction) or between a drug and food (drug-food interaction). Interactions can cause side effects. 

Interactions between alcohol and loperamide or diphenoxylate can lead to nervous system side effects.^16,17 While alcohol may not react with bismuth salicylate, alcohol itself can increase the amount of stomach acid, making it harder for bismuth salicylate to act as intended.¹⁸ Therefore, alcoholic beverages should be avoided. 

 There is no need to avoid any food when taking these medications, as there are no possible drug-food interactions. However, it’s best to avoid spicy or fatty foods as they may upset the stomach further.^5,6,7

Major drug-drug interactions are summarised in the table below. 

Summary

Traveler’s diarrhea (TD) is a self-resolving gastrointestinal infection which occurs when one consumes contaminated food or water. The main symptom of TD is three or more loose, watery stools in one day. Symptom management primarily focuses on replenishing fluids to prevent dehydration and excessive electrolyte loss. Antidiarrheal medications serve as a short-term solution but patients of certain populations ought to be cautious and should seek medical advice before traveling.