"Some people may feel mild bloating or heaviness in their stomach," Chimento says. As your body's stomach acids break down the collagen in supplements, you might experience some wind, queasiness, or a feeling of weight in your abdomen. This should pass relatively quickly, as it's part of the digestive process.

If you feel uncomfortable after taking a collagen supplement, know that you aren’t alone. "Some people may feel mild bloating or heaviness in their stomach," Chimento says. As your body's stomach acids break down the collagen in supplements, you might experience some wind, queasiness, or a feeling of weight in your abdomen. This should pass relatively quickly, as it's part of the digestive process.

If you have a food allergy, collagen supplements might not be for you. "Some are made from seafood or eggs, so if patients have a shellfish or egg allergy, this is something to look out for," Chimento says. If you break out in a rash or have any mild allergic reactions after taking a collagen supplement, take an anti-histamine and consult an allergist. Serious allergic reactions like breathing difficulties mean you need to go to the ER, ASAP.

If you’re vegetarian or vegan, it’s important to know that some collagen can be extracted from fish like cod or mackerel or derived from the membranes of eggshells. Luckily, there are vegan versions that come from sources like algae, so be sure to look at sourcing before you buy your box of supplements.

"Before you take collagen supplements, it is also important to research the brand you are buying and make sure you are taking something that is quality," says Murphy-Rose. Collagen supplements are classified as dietary supplements, so they aren't regulated by the FDA, and that could mean it includes ingredients you don't want. Always talk to your doctor before taking a supplement; they may be able to recommend trusted brands that are known to be high-quality.

Collagen supplements have the potential to block you up. "Too much protein without enough fiber and fluid can lead to constipation," Vanessa Rissetto, RD, a registered dietitian nutritionist and co-founder of nutrition coaching service Culina Health, tells Bustle.

Need to go to the bathroom immediately after taking your morning supplements? The collagen could be to blame. Chimento says diarrhea is listed as one of the rarer side effects of collagen.

Chalk both diarrhea and constipation up to the body attempting to process a lot of collagen proteins. If your gastrointestinal system is having a rough time dealing with your supplements, it could be a sign to take fewer or stay away from them altogether.

"Patients should consult with their doctor before taking collagen supplements to rule out any interactions with medications or supplements already in your daily regimen," Chimento warns.

As an example, some wound-repair gels containing collagen are known to interact poorly with certain topical anesthetics. Chatting to your doctor is particularly important if you experience any digestive problems when it comes to collagen supplements, as it might prevent the active ingredients in your medication from being fully absorbed in your stomach.

While you may be crossing your fingers for longer hair or stronger nails after taking collagen, you definitely won’t see any benefits overnight. A 2019 study published in the Journal of Drugs In Dermatology found that it can take up to 12 weeks for collagen peptide supplements to show a notable improvement in skin elasticity and hydration, so it’ll call for consistency and patience.

All of that said, you might not notice a difference in how you look or feel, even after taking collagen for a couple of months. “Actual benefits to oral collagen supplementation are unclear and lack evidence,” says dermatologist Dr. Sheilagh Maguiness, M.D., adding that many studies are funded by companies and therefore may be biased.

And, remember, supplements and nutraceuticals in the U.S. are not regulated by the FDA. “For those individuals looking for ways to improve the quality and texture of their skin, evidence-based topical therapies such as sunscreen and topical retinoids might be safer and more cost-effective options,” says Maguiness.

You can also boost your body's natural production of collagen by eating certain nutrients. Murphy-Rose suggests eating more foods that contain vitamin C, A, copper, and proline. "That will supplement collagen formation," she says. And that can mean happier skin, muscles, and bones.