Side effects
Sugar Defender Side Effects: Caffeine, Low Blood Sugar, Interactions and Dogs
Sugar Defender side effects have never been measured in a trial, so the likely ones come from single ingredients: caffeine jitters or poor sleep from guarana and green tea, mild stomach upset, and low blood sugar in people on insulin or a sulfonylurea. Xylitol in the liquid is dangerous to dogs. FDA's database lists two 2024 reports naming the brand.
Written by the Sugar Defender label deskUpdated
Overview01
What are the side effects of Sugar Defender?
The side effects of Sugar Defender are not known from the product itself, because no trial has tested it. What we can list are the effects reported for its ingredients.
Doses matter here. The 22 blend ingredients share 200 mg, so most of them sit far below the amounts that caused trouble in studies. Caffeine is the exception: the label prints no amount, so nobody can rule it out.
| Ingredient | Reported effects | Source |
|---|---|---|
| Guarana | Nausea, insomnia; at high doses, heartbeat changes and high blood pressure | (MSKCC, Guarana) |
| Green tea extract | Rare liver injury, mostly from pills; caffeine | (NCCIH, Green Tea) |
| Panax ginseng | Insomnia most often | (NCCIH, Asian Ginseng) |
| Coleus (forskolin) | Low blood pressure, slow heart rate, diarrhea | (MSKCC, Forskolin (Coleus forskohlii)) |
| African mango | Gas, headache, trouble sleeping; one kidney-failure case report | (MSKCC, Irvingia gabonensis (African mango)) |
| Licorice compound | Irregular heartbeat with large or long-term use | (NCCIH, Licorice Root) |
| Capsicum | Stomach irritation and pain | (MSKCC, Cayenne (Capsicum)) |
| Stevia | Nausea, stomach fullness | (MSKCC, Stevia) |
Caffeine02
Does Sugar Defender have caffeine, and can it keep you awake?
Yes, Sugar Defender contains caffeine from guarana seed and green tea leaf, and the label does not say how much.
Guarana is third on the blend list, so it holds at most about 67 mg of the 200 mg blend, and that is extract weight, not pure caffeine. The real caffeine figure is likely smaller, but it is not printed.
FDA cites 400 mg of caffeine a day as an amount most healthy adults handle without trouble. Too much can bring a fast heart rate, jitters, anxiety and insomnia (FDA, Caffeine: how much is too much?). Ginseng adds its own insomnia risk (NCCIH, Asian Ginseng).
Our suggestion: take the dropper in the morning and count it with your coffee. People who are pregnant, sensitive to caffeine or on stimulants should ask a provider first.
Stomach03
Does Sugar Defender cause diarrhea or an upset stomach?
Sugar Defender may upset some stomachs, but the amounts in one dropper are far below those linked to diarrhea in studies.
Forskolin can cause diarrhea (MSKCC, Forskolin (Coleus forskohlii)). Arginine caused diarrhea and nausea at 9-30 g a day (NIH ODS, Exercise & Athletic Performance), and carnitine caused cramps and diarrhea at about 3 g a day (NIH ODS, Carnitine). One milliliter holds 200 mg of blend in total.
Capsicum can irritate the stomach (MSKCC, Cayenne (Capsicum)), and stevia may cause nausea or a full feeling (MSKCC, Stevia). Xylitol is a sugar alcohol, and large amounts of sugar alcohols loosen stools in some people; the label gives no xylitol amount.
If loose stools start with the drops and last more than a few days, stop and call your doctor.
Low blood sugar04
Can Sugar Defender cause low blood sugar with diabetes drugs?
It could add to a low in people who take insulin, a sulfonylurea or a meglitinide. Those drugs can cause lows on their own (NIDDK, Low Blood Glucose).
Chromium may add to the effect of insulin and other diabetes drugs (NIH ODS, Chromium), and the ADA warns that some supplements cause lows when paired with diabetes medicine (ADA, Vitamins & Supplements). Ginseng might lower blood sugar too (NCCIH, Asian Ginseng).
Know the signs before your first dose, and keep fast sugar nearby.
- Shaky or jitteryTrembling hands, feeling nervous
- Sweaty, chillsClammy skin out of nowhere
- Hungry, nauseousSudden strong hunger
- Dizzy, confusedTrouble thinking or speaking clearly
- Fast heartbeatPounding or racing pulse
15-15For many people with diabetes, a low is under 70 mg/dL. Take 15-20 g of fast carbohydrate (juice, glucose tablets), then check again in 15 minutes.
Call 911If someone with a low passes out, has a seizure or cannot safely swallow. Do not give food or drink to someone who is unconscious.
Signs and steps from NIDDK (NIDDK, Low Blood Glucose). Insulin, sulfonylureas and meglitinides can cause lows; supplements may add to them (ADA, Vitamins & Supplements).
Never cut or skip a diabetes dose to make room for a supplement. If lows start, call your doctor; the dose to change is a medical decision.
Interactions05
Does Sugar Defender interact with other medicines?
Several Sugar Defender ingredients can interact with common medicines, which is why the label asks anyone on other medication to consult a physician first.
Most of these findings come from single ingredients at study doses. Still, a pharmacist can check your list against the label in a few minutes.
| Medicine | Ingredient | Concern |
|---|---|---|
| Levothyroxine | Chromium | May reduce absorption (NIH ODS, Chromium) |
| Warfarin and blood thinners | Guarana, forskolin | May raise bleeding risk (MSKCC, Guarana) (MSKCC, Forskolin (Coleus forskohlii)) |
| Blood pressure drugs | Forskolin, arginine, GABA | May add to the drop in pressure (MSKCC, Forskolin (Coleus forskohlii)) (MSKCC, Arginine) (Oketch-Rabah et al., Nutrients 2021 (USP GABA review)) |
| Digoxin | Eleuthero | Raised levels in a case report (MSKCC, Siberian Ginseng (Eleuthero)) |
| MAO inhibitors, tramadol | L-tryptophan | Serotonin concerns (Drugs.com, L-tryptophan) |
| Immune suppressants | Astragalus | Possible interaction (NCCIH, Astragalus) |
| Nadolol | Green tea | Lower drug levels at high doses (NCCIH, Green Tea) |
Grapefruit juice affects some statins and heart drugs (FDA, Grapefruit juice and drugs); the label lists grapefruit seed, a different part. Full guide: supplements and diabetes medication.
Sugar Defender: from $49 a bottle60 mL · 2, 3 or 6 bottles · free US shipping on 3 or 6 · 60-day money-back guarantee
See packsPets06
Why is the xylitol in Sugar Defender a risk for dogs?
Xylitol, one of the sweeteners in Sugar Defender, can drop a dog's blood sugar dangerously within 10 to 60 minutes.
Signs include vomiting, weakness, collapse and seizures. If a dog licks a spill or chews the bottle, call a vet or animal poison control right away (FDA, Paws Off Xylitol).
Xylitol does not trigger the same insulin release in people (FDA, Paws Off Xylitol). Store the bottle up high and wipe drips at once.
Safety record07
Is Sugar Defender safe? What FDA reports show
Sugar Defender has no published safety study, and FDA's public database lists two adverse event reports that name it, both filed in 2024.
The first, filed May 31, 2024, lists increased blood glucose and increased HbA1c. The second, filed July 23, 2024, lists a cardiac disorder and insomnia, with a hospital stay. openFDA notes that a report does not prove the product caused the event (openFDA, CAERS reports naming Sugar Defender).
We found no FDA, FTC or court action naming Sugar Defender as of October 18, 2026. FDA's 2021 warning letters to diabetes-supplement sellers did not include it (FDA and FTC, Diabetes supplement warning letters (2021)).
See also who should not take Sugar Defender.
If something goes wrong08
How do you report a Sugar Defender side effect?
Stop taking the drops, get care if you need it, and file a report with FDA's Safety Reporting Portal.
Stop and call
Stop the drops and call your doctor. For a severe low or chest pain, call 911.
Keep the bottle
Note the date you started, how much you took, and the code on the bottle.
Tell FDA
File at safetyreporting.hhs.gov. FDA says even partial details help (FDA, How to Report a Problem with Dietary Supplements).
For a refund, contact the order desk at +1 (302) 200-3480 within the 60-day window. Our how-to-use guide covers safe daily use.
FAQ09
Sugar Defender side effects: common questions
Does Sugar Defender cause diarrhea?
It might for some people, though no trial has checked. Forskolin, arginine and carnitine can cause diarrhea, but only at doses far larger than one dropper holds (MSKCC, Forskolin (Coleus forskohlii)) (NIH ODS, Exercise & Athletic Performance) (NIH ODS, Carnitine). Xylitol may also loosen stools. If it lasts beyond a few days, stop and see your doctor.
Can Sugar Defender interact with my medications?
Yes, it can. Chromium may cut levothyroxine absorption (NIH ODS, Chromium), eleuthero raised digoxin levels in one case (MSKCC, Siberian Ginseng (Eleuthero)), and L-tryptophan should not be mixed with MAO inhibitors or tramadol without advice (Drugs.com, L-tryptophan). The label asks anyone on medication to consult a physician first.
Is Sugar Defender safe to take every day?
The label directs 1 mL a day for adults, but long-term daily safety has not been studied in the drops. Healthy adults who tolerate caffeine and take no medicines face the fewest flags. Report anything new to your doctor, and read the label warnings before each new bottle.
Can Sugar Defender cause low blood sugar?
On its own, a low is unlikely in healthy adults. The risk rises with insulin, sulfonylureas and meglitinides, which cause lows themselves (NIDDK, Low Blood Glucose), because chromium may add to them (NIH ODS, Chromium). Shakiness, sweating, hunger or confusion are signs to treat with fast sugar at once.
Does Sugar Defender raise blood pressure?
It could for some people, though nobody has measured it. Glycyrrhizin from licorice is a risk for people with high blood pressure even in small amounts (NCCIH, Licorice Root), and guarana at high doses can raise pressure (MSKCC, Guarana). If you track your pressure, check it during the first weeks.
What are King Sugar Defender side effects?
Kings Sugar Defender is a different product sold on marketplaces under a similar name, and we have not reviewed its label. Its side effects depend on its own formula. Compare its Supplement Facts with the ones on our label pages before assuming the two are the same.
Can Sugar Defender harm the liver or kidneys?
No liver or kidney harm has been tied to the drops. Ingredient reports exist: rare liver injury from green tea extracts (NCCIH, Green Tea), a reversible liver case with gymnema (Drugs.com, Gymnema monograph) and one kidney-failure case with African mango (MSKCC, Irvingia gabonensis (African mango)). Tell your doctor if you have liver or kidney disease.
Who wrote this10
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, CDC, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by Isugardefender, a Sugar Defender U.S. shop, not by the manufacturer or the distributor. We earn money when you buy through our order links.
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