How long to wait after taking medicine on an empty stomach

Have you ever been advised to take a medicine with food? How about taking a medicine with cola or avoiding grapefruit?

Hundreds of medicines have food-related dosing instructions. With four out of five Australians aged above 50 taking daily medication, most people will encounter instructions about medicines and food at some point in their lives – some of which may seem rather strange.

If a medicine isn’t taken as recommended with respect to food, the medicine may not have an effect. Worse, it could lead to side effects. The timing of the meal, the size of the meal, and the types of food and drinks consumed can all affect the body’s response to a medicine.

Absorption of medicines from the gut

Eating food triggers multiple physiological changes, including increased blood flow to the gut, the release of bile, and changes in the pH (acidity) and motility of the gut. These physiological changes can affect the amount of medicine absorbed from the gut into the bloodstream, which can then impact on the body’s response to a medicine.

Certain medicines are recommended to be given with food because the physiological changes after eating can increase the amount of medicine absorbed by the body. Itraconazole capsules (used to treat certain fungal infections), for instance, should be taken with food, and in some cases acidic drinks such as cola, because this product needs an acidic environment to be absorbed.

In other cases, changes in gut secretions and the digestive process can reduce the effectiveness of a medicine. Certain antibiotics, such as phenoxymethylpenicillin (also known as penicillin V), are best taken on an empty stomach as they can be less effective after prolonged exposure to acidic conditions.

Food can act as a physical barrier to the surface of the gut wall and prevent certain medicines being absorbed into the bloodstream.

Specific components of food, such as calcium or iron, may also bind to certain medicines. This can reduce absorption into the bloodstream, and lead to reduced effectiveness. For this reason, osteoporosis medicines risedronate and alendronate must be taken on an empty stomach with water only.

Taking certain medicines with food can reduce the risk of side effects. Diabetes medicines such as gliclazide or glimepiride (belonging to the group of medicines known as sulfonylureas), for example, should be taken with food to reduce the risk of low blood sugar.

Taking medicines such as ibuprofen (for pain and inflammation) or metformin (for diabetes) with food is also recommended to reduce nausea and stomach upset.

Does size really matter?

The relationship between meal size and medicine effect has not been widely studied. If you need to take a medicine with food and it’s not mealtime, sometimes a snack is enough. But for some medicines, the size of the meal is important. Orlistat, for example, reduces the absorption of fats from food to assist weight loss, so it’s important to take this medicine with main meals for optimal effect.

Meal composition can also be important. Eating foods high in fibre, protein or fat can impact on the absorption of some medicines.

Drinks such as tea, coffee, milk and fruit juice can also affect the way certain medicines act in the body.

Dairy products should be avoided within two hours of taking antibiotics such as ciprofloxacin or norfloxacin, however they can be eaten at other times.

You may need to avoid grapefruit altogether as it can interfere with the metabolism (processing) of certain medicines in the body, leading to side effects.

Medicine labels demystified

Check medicine labels carefully for advice about food or drinks. Unless otherwise advised, tablets or capsules should be swallowed with water.

If the label states “take with or after food”, it means the medicine should be taken during the meal, or within half an hour of eating.

To take a medicine “on an empty stomach”, check you have not eaten in the past two hours, and wait at least half an hour after taking the medicine before eating again, unless the label states otherwise.

Finally, it’s important to take medicines at the same time each day and be consistent with respect to food and drinks.

If you have specific questions about taking medicines with food, ask your pharmacist for further advice, check the consumer medicines information (CMI) for each medicine, or call Medicines Line on 1300 633 424.

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Key takeaways:

• Some medications work better when taken on an empty stomach. Common examples include thyroid medications, bisphosphonates, and sucralfate (Carafate).

• The general rule of thumb is to take your medication either 1 hour before or 2 hours after a meal. But how long you should wait before eating or drinking can differ depending on the medication.

• Check with your pharmacist or healthcare provider if you should take any of your medications on an empty stomach. Make sure you understand what to separate from your medications, and for how long.

If you’ve ever been told to take medication on an empty stomach, you might still have a few questions about how to do so. For instance, can you still enjoy your morning cup of coffee after taking your pill? And how long do you need to wait after you’ve taken your medication before eating?

Well, a lot of research has gone into finding out how foods and drinks affect medications. And, depending on the medication, the answers to your questions might vary.

Why should certain medications be taken on an empty stomach?

Generally, there are a few reasons why some medications need to be taken on an empty stomach. These include:

• Slowed absorption: Food can delay the time it takes for certain medications to be absorbed by your body. This can cause the medication to take longer to work.

• Lower absorption: Some foods, drinks, and supplements can lower the amount of medication that gets into your body. This usually happens when these foods or drinks attach to the medication in your stomach.

• Faster or slower break down: Some juices, like grapefruit juice, can cause certain medications to get broken down faster in your body. If this happens, your medication might not work as well. Juices can also sometimes cause medications to get broken down more slowly. This can lead to a build up in your body and cause more side effects.

What does it mean to take a medication on an empty stomach?

Taking a medication on an empty stomach typically means you do so either 1 hour before or 2 hours after meals. Although this is a good general rule to follow, some medications have more specific instructions. So, it's important to understand what this means for your medication.

After a meal it normally takes around 1 hour and 30 minutes to 2 hours for your stomach to empty. But, the type of meal you eat plays a role in how fast it moves through your stomach. For example, a high fat meal can slow down the time it takes for your stomach to empty. 

What about coffee, juice, or other medications? The answer will differ depending on the medication. But try not to mix any foods, drinks, or other medications without speaking with your healthcare provider or pharmacist first. This is because even your morning coffee could affect the way some medications get absorbed into your body.

Next, we’ll discuss a few common examples.

1. Thyroid medications

If you have hypothyroidism, you may be taking a thyroid medication like levothyroxine (Synthroid, Levoxyl, Tirosint). If so, you’ve probably been instructed to take it first thing in the morning on an empty stomach. That’s because certain foods and drinks can change the way it works in your body. 

For example, walnuts, high-fiber foods, and soybean flour may affect levothyroxine absorption. And common breakfast drinks, like grapefruit juice, coffee, and milk, have been shown to do the same. 

Levothyroxine should be taken 30 to 60 minutes before breakfast. This includes your morning coffee. Take it at least 4 hours before or after other medications, unless you’ve checked with your healthcare provider first.

Interactions with other thyroid medications, like Armour Thyroid and NP Thyroid, haven’t been researched. That’s because these medications were grandfathered instead of going through the FDA approval process. They contain similar ingredients to levothyroxine, so it’s still typically recommended to take them on an empty stomach. 

2. Bisphosphonates

Alendronate (Fosamax), ibandronate (Boniva), and risedronate (Actonel) are a few examples of bisphosphonates. They’re a group of medications that help prevent bone breakdown and are used to treat osteoporosis.

Some foods, antacids, and supplements can attach to bisposphonates in your stomach. This interferes with absorption. You may need to avoid taking these medications with juice, too. One study showed orange juice lowered alendronate absorption by about 60% compared to water.

For alendronate and risedronate, it’s recommended to take your dose at least 30 minutes before your first food, drink, or medication of the day. It’s recommended to wait at least an hour with ibandronate.

Drink a full glass (6 oz to 8 oz) of plain water with your pill. This helps the tablet move down to your stomach faster. By doing so, you can prevent damage to your esophagus (the tube that moves food from your mouth and into your stomach). 

3. Sucralfate

Sucralfate (Carafate) is an oral medication that’s used to treat intestinal ulcers. It works by forming a protective coating over the ulcer.

Sucralfate must be taken on an empty stomach. This means at least 1 hour before or 2 hours after a meal. If it’s taken with food, the medication may not coat the ulcer properly.

If you’re also taking an antacid, don’t take it within 30 minutes before or after taking sucralfate. Otherwise, it could lower the ability of sucralfate to attach to your ulcer.

4. Sildenafil (Viagra)

Sildenafil (Viagra) is a medication commonly used to treat erectile dysfunction (ED). And while it can be taken with or without food, taking it after a high fat meal (think cheeseburger and fries) can make it take longer to work.

Your best bet for sildenafil to work as fast as possible is to take it on an empty stomach. But, if you need to take it with food, make sure to choose low-fat options.

5. Captopril

Captopril is a medication used to treat high blood pressure and heart failure. It’s also used to treat kidney problems in people with Type 1 diabetes.

Taking captopril with food can lower its absorption and cause it to not work as well. Take it 1 hour before or 2 hours after meals to make sure you’re getting the most from your medication.

6. Bethanechol

Bethanechol is a medication used to treat urinary retention. It should be taken on an empty stomach to avoid nausea and vomiting. Specifically, you should take it 1 hour before or 2 hours after meals.

You might find this hard to do since bethanechol is typically taken 3 or 4 times a day. It might be helpful to set an alarm and plan to take it around your meal schedule.

7. Ampicillin

Some antibiotics can be taken with or without food. But ampicillin is one that must be taken on an empty stomach.

Research shows that when it’s taken with food, the absorption is delayed and less of it gets into your body. This can make it less effective at treating your infection. It’s recommended to take ampicillin 30 minutes before or 2 hours after meals.

8. Zafirlukast

Another medication that can be affected by food in your stomach is zafirlukast (Accolate). Zafirlukast is taken by mouth twice daily to prevent and treat asthma in adults and children ages 5 and older.

During clinical studies, researchers found that food lowered the amount of zafirlukast absorbed into the body by 40%. Take this medication at least 1 hour before or 2 hours after meals.

9. Proton pump inhibitors

Proton pump inhibitors (PPIs) are medications commonly used to treat gastroesophageal reflux disease (GERD). They work by blocking the final step of acid secretion in your stomach.

Food triggers your stomach to produce acid. So, you’ll want your PPI to block acid secretion before acid gets triggered. That’s why it's typically recommended to take PPIs before meals. The one exception is pantoprazole (Protonix) tablets, which work just as well with or without food.

Some PPIs don’t have specific recommendations for timing. But the general rule of thumb is 30 to 60 minutes before a meal. However, esomeprazole (Nexium) should be taken at least 1 hour before meals.

Many foods and drinks can cause certain medications to not work as well. In this case, you may need to take them on an empty stomach. What this means can depend on your particular medication.

It’s important to know if any of your medications should be taken on an empty stomach. If you aren’t sure about timing or specific interactions, ask your healthcare provider or pharmacist to give you more details.

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