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Prenatal vitamins have many benefits for you and your growing baby, but sometimes they can cause issues.

Although usually not extreme, you may experience a set of side effects that can trigger or make pregnancy symptoms worse. Additionally, certain nutrients or minerals contained in the supplement may be to blame.

In this post, we’re discussing prenatal vitamin side effects and what to do about them.

Although prenatal supplements aren’t always necessary, most doctors recommend them because women often aren’t sure about the exact vitamins they’re getting through their diet. They also contain a very critical pregnancy nutrient: Folic acid.

Other important nutrients include:

  • Calcium to prevent bone density loss and support baby bone growth
  • Iodine for thyroid function and to prevent miscarriage and stillbirth
  • Iron to make extra blood and move oxygen to your baby
  • Other essential vitamins and minerals to improve your health and therefore have a healthier pregnancy

Side Effects of Prenatal Vitamins

Most women who take prenatal vitamins don’t experience side effects. If they do, the symptoms are usually mild.


Prenatal vitamins may cause nausea for a few reasons. If you’re experiencing morning sickness, it can be made even worse if your prenatal vitamin is a large capsule that can barely slide down your throat. If you’re someone bothered by large pills, it can be enough to make the pregnancy symptom even worse.

The taste of some vitamins may also throw your stomach for a loop. When you’re expecting, you’re often more sensitive to smells and tastes. While a fruity chewable may have been tasty before, it could be a bad idea now. Even if there’s no immediate taste, the aftertaste may bother you. For example, some people can’t stand a fish oil flavor left in their mouths.


Most prenatal vitamins contain iron. While it’s an important mineral for you and your baby, it can have some side effects, the most popular being constipation. If you notice you’re having trouble going to the bathroom after beginning a vitamin with iron, it could be the cause. Try drinking more water, gradually adding fiber to your diet and exercising. On the other hand, some people also experience diarrhea from iron.

Stool Color

Another bathroom-related side effect is the color change of your poop. Sometimes introducing a prenatal can mean a change in your stools. For example, iron can cause darker poops. Other women may experience green stools.

Stomach Pain

Stomach pain is another problem that could be caused by the iron in your prenatal. Some people experience cramps after taking their supplement. If the pain is severe, stop using the brand and ask your doctor for recommendations.

Change in Urine Color/Odor

This side effect may be attributed to vitamin B. B vitamins, folic acid and riboflavin can make your urine a bright yellow if your body has an excess of it. This is because they contain yellow-orange or yellow-green pigments. Vitamin B may also give your urine a sulfur-like odor. Although you may be aware of the change, it’s usually harmless.

Most women don’t have serious reactions, but you should seek medical attention if you experience the following from your prenatal vitamin:

  • Bloody stools
  • Extreme stomach pain or cramps
  • Fever
  • Allergic reactions, such as hives, itching, swelling, wheezing, trouble breathing, etc.

What To Do About Prenatal Vitamin Side Effects

If you’re experiencing prenatal vitamin side effects, there’s a few things you can do.

Identify the Cause of the Side Effect

If you suspect a certain vitamin or mineral is causing the problem, you can search for a brand that includes less of that vitamin (or a different form of it) and aim to get it through your regular diet instead. For example, if you think iron is causing stomach upset, you can choose a vitamin with fewer milligrams or none at all. Instead, you can get iron through foods or from a separate supplement such as liquid iron, which may be more gentle on the stomach.

Similarly, if you know the size or taste of a vitamin is causing nausea, choose smaller tablets or brands without flavor.

Try Different Brands

If you’re not sure what is causing your side effect, you may wish to keep trying brands until you find one that works for you. Reading online reviews can also help. If you experience stomach upset from vitamins and several reviews mention it as a side effect, it may not be your best option. Keep in mind that prenatal vitamins come in different forms: capsules, tablets, chewable tablets, chewable gummies and liquid. If one doesn’t work for you, try a different type. While you’re experimenting, remember to buy in small quantities and stock up when you find the best vitamin for you.

Try Taking it at a Different Time

If you normally take your prenatal in the morning and experience side effects, see if taking it at night makes you feel any better (and vice versa). If the brand you’re using only requires you to take one per day, cut it in half and take one half in the morning and the other at night. Try varying times throughout the day to see if it makes a difference.

Take Prenatal with Non-Dairy Creamy Foods/Drinks

Most prenatals should be taken with food or else you may experience even worse nausea. If the foods you’re choosing to take with it aren’t helping, try something different. Creamier foods and drinks that allow the capsule to more easily slide down the throat may help. For example, try taking it with:

  • Smoothies
  • Applesauce
  • Juices with creamier textures
Ask Your Doctor

Explain your side effects to your doctor and he or she may try to pinpoint what’s causing it. Ask for recommendations that are more likely to work for you. If the side effects are unbearable, he or she may suggest you get a separate supplement for the most important nutrients—such as folic acid—and aim to get the rest through your diet. Alternatively, they may suggest ways to treat the side effects instead.

Prenatal Vitamin Recommendation

Finding a supplement that works for you is important since you should continue taking it while breastfeeding. We recommend the MamaNuture Premium prenatal vitamins for several reasons:

  • Curated compilation of 25 nutrients and vitamins
  • 300mg DHA to help your baby’s visual and cogitative development
  • Optimal ratios of absorption
  • Contains Quatrefolic bioactive folate, iron and B12 to help prevent neural tube defects
  • No artificial dyes or additives
  • Made in the USA and bottled in a state-of-the-art GMP certified facility
  • Kosher
  • Affordable

Good for those with prenatal sensitivity:

I can tell they work because I’m sooo sensitive to any pills but these ones are awesome.” –Annika M.

If you are sensitive like me then this is exactly what you need! Can’t take anything else.”— Lylah H.

Good choice for nauseous mothers-to-be:

Great vitamins, without feeling nauseous as the other brands out there and healthy too.”—Morgan M.

Simple ingredients:

I like how simple the ingredients are and would buy again.”—Nylah H.

No weird aftertaste:

I need another bottle soon!! I really like that you don’t burp the aftertaste of the pills.”—Dylan N.

Good for sensitive stomachs:

So happy this doesn’t make me constipated like Materna. I was so bloated and in pain and could not take laxatives obviously.”—Delaney K.

Possible energy-boosting benefits:

I feel like it gives me the boost of energy I need especially when I’m exhausted with my toddler and preggers.”—Janiyah W.

I feel like I have more energy with these.”—Sandra S.

Get MamaNuture Premium Prenatal Vitamins for $29.95

Automatic Vitamin Detector

If you’re worried about getting all of the essential vitamins and nutrients, you may consider buying a vitamin detector. This pen-like device is placed on certain points on your skin to read your levels. You can view your results and suggestions on the connecting app. This is useful if you’re not sure how much of which nutrients you’re getting through your diet. Since it also stores data from previous readings, you can view how your intake is improving throughout your pregnancy.

If you purchase the family tracker, it gives you the ability to track the vitamin levels of your baby when she’s born (or anyone else in the family).

Get the personal vitamin tracker for $149.95

Get the family vitamin tracker for $199.95


Most women don’t experience any side effects from prenatal vitamins. The most severe side effects are stomach cramping and constipation caused by the iron contained in most supplements. Some factors can also trigger or make pregnancy nausea worse. This includes the size or form of the vitamin along with any odors, tastes or aftertastes it has.

If you experience negative side effects, use the tips above to mitigate them or find a brand that works for you. If all else fails or if your side effects are extreme, contact your doctor to ask for recommendations.

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