Yes – typically it’s ok to take medication while you fast.
But it depends on the specific medication.
For example, Tylenol is pretty safe, but insulin and other diabetes medications need to be carefully monitored while fasting.
The duration of your fast also matters.
For example, a 3-day water fast will affect your blood sugar and blood pressure a lot more than if you’re just doing daily “intermittent” fasting.
Today I’ll share an overview of medications that are fairly benign while fasting, and others that should be monitored closely.
Keep in mind, you’ll need to consult your own medical provider for all medication adjustments — I can’t give individual medical advice online.
That being said, I think you’ll find it valuable to have a basic understanding of why some medications are safer than others while fasting.
Does Taking Medication “Break” Your Fast?
Generally speaking, medications don’t “break” a fast — assuming you don’t take them with food.
A couple of caveats:
Some medications (like cough syrup) may have a lot of added sugar. So check the ingredients, especially if it tastes sweet. If there’s more than a trivial amount of sugar, try to avoid it if you can.
Medications can also have added starch, for texture. So try to look at both the active and inactive ingredients, to see what’s actually in your medicine.
Most pills have either zero calories or pretty close — it’s more often the liquids that are an issue.
When Should I Take My Medication During Intermittent Fasting?
Daily intermittent fasting (a.k.a. time-restricted eating) means eating all your food in a shorter window of time, like 10am-7pm (9 hours).
The question of when to take your medication during intermittent fasting really boils down to one thing-
Do you need to take the medication with food?
If so, see if you can take it during your “eating window”. If not, take it whenever it would typically be recommended (like morning versus bedtime).
What About Medications During Extended Fasting?
If you’re fasting for days at a time, obviously it’s hard to take your medication with food.
If you absolutely NEED to take the medication with food, here’s a tip:
Have a couple tablespoons of chia seeds (soaked in water) beforehand, or some bone broth. They won’t really disrupt your fast that much, but they give your med something to mix with in your stomach.
Taking Over The Counter (OTC) Medications While Fasting
It’s usually okay to take non-prescription medications while you fast.
For example, using Tylenol for a headache is perfectly fine.
Ibuprofen, naproxen, and other “NSAIDs” are mostly fine as well, though they can be hard on your stomach. So if you have the choice, use Tylenol instead.
Similarly, aspirin is usually okay but can irritate your stomach or make you feel nauseous during a fast. So it may be better NOT to take on an empty stomach.
(Sidenote: Another common category of medications that cause nausea are iron supplements.)
Keep in mind the usual caveats about sugar / starch in your OTC medications as well – especially liquids like “syrup”.
Diabetes Medications Can Be Dangerous – Monitor Closely
By definition, people with diabetes have HIGH blood sugar (glucose). So they take medications to make it LOWER.
When you fast, your blood sugar gradually comes down, naturally. It may go even lower than you’d normally expect (i.e. lower than 70 mg/dL) — and that’s typically fine, because your brain is now running on ketones instead of just sugar.
But if you take meds that FORCE your blood sugar even lower, that could be dangerous, even life-threatening.
The bottom line?
If you’re on any diabetes medications that lower your blood sugar, you need to work with your medical provider to adjust the dose when you fast.
With that in mind, let’s explore some specific diabetes meds.
You Won’t Need as Much Insulin When Fasting
Under normal circumstances, your pancreas secretes insulin to lower your blood sugar after a meal.
But if your pancreas can’t make insulin anymore (type 1 diabetes), or your body becomes “resistant” to the effects of insulin (type 2 diabetes), you may have a prescription for insulin injections.
Here’s the bottom line:
If you’re fasting, you won’t need as much insulin, so start low and go slow. You can always add more later.
If you inject too much insulin, you’ll end up needing to drink sugary stuff (like juice) to get your blood sugar back up. And that defeats the purpose of fasting.
Coming Off Insulin
Sometimes diabetic patients have a little harder time regulating their blood sugar right after they stop injecting insulin. It’s kind of like their system is a little “rusty”.
Sometimes this leads to mild problems with low blood sugar, but usually that passes within a few weeks.
In the meantime, using “training wheels” like bone broth or chia seeds (etc.) can give you a little extra boost to keep your blood sugar more stable while fasting.
Other Diabetes Medications
Medications like glipizide, glimepiride, or glyburide (category = “sulfonylureas”) stimulate your pancreas to make more insulin. That’s almost the same as if you were injecting insulin, because either way your insulin level goes up.
So you’ll probably need to lower the dose of these meds as well, during a fast.
On a related note, when we have patients come to the ER for hypoglycemia, it’s usually because they overdosed on either insulin or a sulfonylurea.
Diabetes medications that don’t mess with insulin are less likely to be a problem. But always check with your provider to be safe.
What About Metformin?
Metformin doesn’t directly lower your blood sugar, so it’s pretty safe to use while you fast.
However, it can cause GI upset, so just like aspirin or ibuprofen you may not want to take it on an empty stomach.
If you’re doing daily intermittent fasting, you can probably just take metformin with your food. If you’re doing longer fasts, you may want to stop taking it, temporarily*.
(*In theory, metformin could make prolonged fasting more difficult, because it partially blocks a process called “gluconeogenesis”, which is how your liver makes new glucose out of fat or protein molecules.)
Blood Pressure Medications Need To Be Monitored As Well
Generally speaking, your blood pressure gradually gets lower the longer you fast.
That’s often a good thing — many (if not most) adults have abnormally high blood pressure.
Here’s how it works-
When your insulin is high (from eating too many processed carbs, for example), you retain more salt and water. So your blood pressure goes up.
When your insulin is lower (like after fasting), you pee out more sodium / salt. So your blood pressure gradually drops.
(That’s why it can be helpful to drink salty stuff when you’re fasting.)
Some blood pressure medications also make you pee out more of other electrolytes, like potassium and calcium.
If you’re fasting while on blood pressure medication, you may need to temporarily stop the medication, or at least lower the dose.
So work with your provider on the specifics.
Other Prescription Medications
Diabetes and blood pressure medications are the biggest thing to keep an eye on.
But there are countless other medications to consider. Let’s look at a few common examples.
People with low thyroid typically take a replacement medication called “levothyroxine”.
Generally, it’s fine to keep taking thyroid replacement while you fast.
On a related note, it hasn’t been studied very much, but some people report their thyroid function improves after fasting for a while. It kind of makes sense, because insulin and thyroid function are closely connected.
Fasting / feasting cycles are not only great for reducing body fat, they also help other things in your body work better — likely including thyroid hormones.
On the off-chance you need to take antibiotics while you’re fasting, typically it’s okay.
Some antibiotics are meant to be taken with food. So if you’re doing daily intermittent fasting, you can just take it during one of your meals. If you’re doing a longer fast, you could use a supplement like chia seeds so your stomach isn’t empty.
Whether you’re fasting or not, keep in mind antibiotics often cause GI side effects, such as nausea or diarrhea.
Generally speaking, cholesterol medications (like Lipitor / atorvastatin, or other “statins”) are overrated, and they probably do more harm than good in the majority of cases.
If you wanna understand why, watch this lecture from Dr. Nadir Ali:
That’s not the main point of this article, but since we’re on the topic it seemed worth mentioning. 😉
In the short-term, it’s generally okay to keep taking cholesterol meds while you fast (but temporarily discontinuing them is ok too).
One thing to know about steroid medications (like prednisone, Medrol dose packs, etc.) is that they raise your blood sugar. So it actually kinda makes sense to fast (or at least avoid carbs) when you’re taking them, so that your blood sugar doesn’t go up as much.
On the other hand, steroids can irritate your stomach, so you may not want to take them on an empty stomach.
It’s a bit of a catch-22.
Medications that reduce your stomach acid production (like Prilosec / omeprazole, or Nexium / esomeprazole) are generally ok to take while fasting.
For instance, I used to have reflux problems, so sometimes I took omeprazole during prolonged fasts. And it wasn’t a problem.
Meds that relieve indigestion or heartburn in the short-term (like antacids, or Pepto Bismol) are mostly ok as well. But watch out for added sugar or sweeteners (which may stimulate cravings).
Some people lump vitamins in with medications, but they’re kind of a different category.
Either way, it’s generally OK to take vitamins when you’re fasting (though perhaps unnecessary).
As above, make sure there’s not a bunch of sugar in your vitamins (like with gummies), and not too many calories either (e.g. fish oil can add up pretty quick).
FYI, I talked a little more about vitamins and fasting in my article on what breaks a fast.
Can you take medication while you fast?
In general, yes. But it depends on the specific medication, and how long you’re fasting.
Non-prescription medicines are usually ok, but watch out for added sugars and starches. And some (like ibuprofen or aspirin) may be better to avoid on an empty stomach.
Your blood sugar and blood pressure will gradually go down when you’re fasting, which is highly beneficial!
But it also means you’ll need to lower the dose of your diabetes and blood pressure medications in most cases. So work with your medical provider.
There are countless other prescription and non-prescription medications, and I could never cover all of them. But I’ve included several common examples.
Consider each medication on a case-by-case basis, and always consult your medical provider for adjustments.
Hopefully you found this article helpful!
If you’re looking to tap into the health benefits of fasting, why not check out my Complete Beginner’s Guide to Intermittent Fasting? Or you can download my Easy Fasting Guide by filling out the form below. 🙂