Glucosamine Side Effects: What to Know Before You Take It

Glucosamine is one of the most widely used joint supplements there is, and for most people the worst it does is upset the stomach. A few groups do need to check with a doctor first, though, and it's better to know which before you open the bottle.

The Common Side Effects of Glucosamine

According to Mayo Clinic, glucosamine sulfate taken by mouth can cause:

• Nausea
• Heartburn
• Diarrhea
• Constipation

All four are stomach complaints, and they're usually mild. If you get one, the first fix is simple: take your capsules with a meal instead of on an empty stomach. Splitting the daily amount between two meals helps too.

Less Common Side Effects

A smaller number of people report:

• Drowsiness
• Headache
• Skin reactions, like a rash or itching

Stop taking it and call your doctor if you get a rash, hives, swelling or trouble breathing. Those can be signs of an allergic reaction.

Who Should Talk to a Doctor First

For most healthy adults, glucosamine is a low-risk supplement. These are the situations where you should ask before you start:

If you...	Here's why
Take warfarin	Glucosamine, alone or with chondroitin, may strengthen the effect of this blood thinner and raise the risk of bleeding
Have a shellfish allergy	Many glucosamine supplements are made from shellfish shells
Have glaucoma	There's some concern glucosamine might raise pressure inside the eye
Have asthma	Glucosamine might make asthma worse in some people
Have diabetes	Most research shows no real effect on blood sugar, but watch your numbers when you start
Are pregnant or nursing	There isn't enough research to say it's safe
Take acetaminophen regularly	Taking the two together might make both less effective
Have surgery scheduled	Tell your surgeon about every supplement you take

Glucosamine and Shellfish Allergy

Most glucosamine in supplements comes from the shells of shellfish like shrimp, crab and crayfish. Some is made in a lab instead.

Shellfish allergies are generally triggered by the meat, not the shell, and allergic reactions to glucosamine are rarely reported. But a shellfish allergy can be serious, so this isn't one to guess on. If you're allergic, check the label for a shellfish statement and talk to your doctor before you take any glucosamine product.

The glucosamine in Joint comes from shellfish (crayfish), and the label says so.

Does Glucosamine Raise Blood Sugar or Blood Pressure?

Blood sugar. Glucosamine is a type of sugar, so early on there was concern it might raise blood sugar. Most research since then shows it doesn't have a meaningful effect on blood sugar control in people with type 2 diabetes. If you have diabetes, the sensible move is to check your numbers a little more often for the first few weeks.

Blood pressure. There was a similar early concern about blood pressure. Most research shows glucosamine doesn't raise it.

How to Take Glucosamine and Avoid Side Effects

1. Take it with food. This is the fix for most stomach complaints.
2. Stick to the label. 1,500mg a day is the amount used in most research. More isn't better.
3. Take it every day. Glucosamine isn't a painkiller and it doesn't work in an hour. Give it several weeks of daily use before you judge it.
4. Tell your doctor and pharmacist. Especially if you take a blood thinner or any other daily medication.

Glucosamine is only one of the joint ingredients with research behind it. We ranked the rest in best joint supplement for knees, and we cover turmeric in turmeric for joint health.

What's in Joint

Kneeling on concrete, climbing in and out of a truck, ten hours on a hard floor: that's the kind of wear we built Joint for. One 3-capsule serving has:

Ingredient	Per serving
Glucosamine sulfate	1,500mg
Boswellia serrata	200mg
Chondroitin sulfate	150mg
Turmeric root	150mg
Quercetin, methionine, MSM and bromelain	25mg each

• The researched amount of glucosamine sulfate, 1,500mg, in one daily serving
• Daily joint comfort support for knees, hips and shoulders
• $34.99, or $29.74 on subscription, with no subscription required
• Third-party tested, hormone-free and drug-test safe, made in the USA with global ingredients
• Backed by our 30-day money-back guarantee

Want omega-3s alongside it? The Joint Support Pack pairs Joint with our Omega softgels. More on that combination in can you take turmeric and fish oil together.

Glucosamine Side Effects: Common Questions

What are the side effects of glucosamine?
The most common are nausea, heartburn, diarrhea and constipation. Less often, people report drowsiness, headache or skin reactions. Taking glucosamine with food usually helps with the stomach side effects.

Is glucosamine safe to take every day?
Glucosamine sulfate appears to be safe for most adults when taken in appropriate amounts. 1,500mg a day is the amount used in most research. Check with your doctor first if you take warfarin or have a shellfish allergy, glaucoma, asthma or diabetes.

Who should not take glucosamine?
People taking warfarin should not take it without their doctor's approval, because it may raise the risk of bleeding. People with a shellfish allergy, glaucoma, asthma or diabetes, and women who are pregnant or nursing, should talk to a doctor first.

Can you take glucosamine if you are allergic to shellfish?
Talk to your doctor first. Many glucosamine supplements are made from shellfish shells. Shellfish allergies are usually triggered by the meat and not the shell, and reactions to glucosamine are rarely reported, but check the label and get medical advice before taking it.

Does glucosamine raise blood sugar?
Most research shows glucosamine does not have a meaningful effect on blood sugar control in people with type 2 diabetes. If you have diabetes, monitor your blood sugar when you start and tell your doctor you're taking it.

Does glucosamine raise blood pressure?
Most research shows it does not. There was early concern about blood pressure, but studies have generally not found that glucosamine raises it.

Does glucosamine interact with blood thinners?
Yes, with warfarin. Glucosamine, alone or combined with chondroitin, may strengthen warfarin's effect and raise the risk of bleeding. Talk to your doctor before combining them.

Does glucosamine upset your stomach?
It can. Nausea, heartburn, diarrhea and constipation are the most common side effects. Taking it with a meal, or splitting the daily amount between two meals, usually helps.

How much glucosamine should you take a day?
1,500mg a day is the amount used in most research. One 3-capsule serving of Joint has 1,500mg of glucosamine sulfate, along with boswellia, chondroitin and turmeric. It's $34.99, or $29.74 on subscription, with no subscription required.

Will Blue Collar Nutrition supplements cause a failed drug test?
Absolutely not. All products are natural, hormone-free, and do not contain any amphetamines or substances that would trigger a failed drug test.

More on Joints

• Best Joint Supplement for Knees: ingredients ranked by evidence
• Turmeric Supplement for Joint Health
• Can You Take Turmeric and Fish Oil Together?
• Joint Support Pack: Joint plus Omega

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This article is for general information and is not medical advice. Side effect and interaction information is drawn from Mayo Clinic and other published medical references. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Consult your physician before beginning any supplement regimen, particularly if you have an existing medical condition or take prescription medication.