Side effects
Synaptril Side Effects: Stomach, Sleep, Liver Signs and Interactions
Synaptril side effects have never been measured, because no trial has tested the capsule. Its six ingredients are linked to mild stomach upset, loose stools and, with CoQ10, some trouble sleeping. Turmeric carries a rare risk of liver injury. The bigger issue is interactions with warfarin, diabetes medicines and some antibiotics.
Written by the Synaptril label deskUpdated
Overview01
What are the most likely Synaptril side effects?
The most likely Synaptril side effects are mild stomach upset and loose stools, based on what each ingredient does on its own. Nobody has recorded side effects of the capsule itself, because no trial of it exists.
The amounts matter. Only magnesium is printed, at 80 mg. Our label math suggests the other five lines share roughly 5-175 mg, far below the doses where most problems were reported. That makes common side effects less likely, but it does not rule out rare ones.
| Blend line | Reported side effects | Source |
|---|---|---|
| Magnesium glycinate | Diarrhea, nausea and cramps at high supplement intake | NIH ODS (NIH ODS, Magnesium) |
| Alpha-lipoic acid | Nausea, indigestion, rash, low blood sugar | MSKCC (MSKCC, Alpha-Lipoic Acid) |
| Butcher's broom | None on record at the EU review | EMA (EMA, Rusci rhizoma (butcher's broom)) |
| L-carnitine | Nausea, diarrhea and fishy odor near 3 g a day | NIH ODS (NIH ODS, Carnitine) |
| Turmeric extract | Stomach upset, rash; rare liver injury | NCCIH, LiverTox (NCCIH, Turmeric) (NIH LiverTox, Turmeric) |
| Coenzyme Q10 | Mild insomnia, nausea, diarrhea, poor appetite | MSKCC (MSKCC, Coenzyme Q10) |
Stomach02
Can Synaptril upset your stomach?
Yes, Synaptril can upset your stomach, though at one capsule a day it is usually mild if it happens. Five of the six lines list stomach effects at higher doses.
Magnesium is the main suspect for loose stools, since excess supplement magnesium causes diarrhea (NIH ODS, Magnesium). The 80 mg in a capsule is well under the 350 mg daily limit, unless you add antacids, laxatives or another magnesium product.
In the one turmeric memory pilot, 4 people on curcumin and 2 on placebo reported stomach effects (Small et al. 2018, curcumin and memory). That trial used a different, high-absorption form.
Take the capsule with a meal, not on an empty stomach. If diarrhea or cramps last more than a few days, stop and ask your doctor. Timing tips are on how to take Synaptril.
Liver03
What liver warning signs should Synaptril users watch for?
Watch for yellow skin or eyes, dark urine, unusual tiredness, nausea and poor appetite. Stop the capsules and call a doctor if any appear (NCCIH, Turmeric).
The concern is turmeric. NIH's LiverTox rates it a well-documented cause of liver injury, usually starting 1 to 4 months after someone begins taking it (NIH LiverTox, Turmeric). Most cases clear 1 to 3 months after stopping, but a few have been severe.
Most reported cases involved high-absorption curcumin products; Synaptril lists a standard extract in a likely small amount. More on turmeric and the liver.
Sleep04
Can Synaptril affect your sleep?
Synaptril may disturb sleep in a few people, mainly because coenzyme Q10 is linked to mild insomnia (NCCIH, Coenzyme Q10). No caffeine or other stimulant appears on the label.
If your nights get worse after you start, move the capsule to the morning, or stop if that fails.
Magnesium sometimes gets credit for better sleep, but that evidence is small and low quality (Mah & Pitre 2021, magnesium and sleep). Do not count on either effect.
Interactions05
Is Synaptril safe with your medicines?
Synaptril is not automatically safe with every medicine. Turmeric and CoQ10 can affect warfarin, alpha-lipoic acid may lower blood sugar, and magnesium can block some antibiotics and bone drugs.
Turmeric may raise bleeding risk with anticoagulants or antiplatelets (MSKCC, Turmeric). CoQ10 has weakened warfarin in a few cases, so INR checks may need to be closer in the first 2 weeks (Linus Pauling Institute, Coenzyme Q10). Alpha-lipoic acid may add to insulin or other diabetes drugs (Linus Pauling Institute, Lipoic Acid).
CoQ10 and turmeric may also interfere with some chemotherapy and radiation (MSKCC, Coenzyme Q10) (MSKCC, Turmeric). Keep taking prescribed medicine, and tell every prescriber about the capsule. Answer the five questions below before you start.
A fuller list sits in our guide to brain supplements and medications.
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See packsHigher risk06
Who is more likely to have problems with Synaptril?
People with kidney disease, diabetes, a bleeding risk or an upcoming surgery face more risk from Synaptril. So do children and pregnant or nursing women, whom the label excludes.
Weak kidneys clear magnesium poorly, which raises the chance of buildup (NIH ODS, Magnesium). Alpha-lipoic acid has been tied to a rare autoimmune low blood sugar, with about 27 cases reported, mostly in Japan (MSKCC, Alpha-Lipoic Acid). Turmeric supplements may raise kidney stone risk (MSKCC, Turmeric). Before surgery, tell your team about every supplement (NCCIH, Using Supplements Wisely).
The label's own warning
"Do not exceed recommended dose. Not for use for those under the age of 18 or pregnant or nursing mothers. Consult with a physician prior to use especially if you are taking a medication or have a medical condition."
Stop and report07
What should you do if you have a reaction to Synaptril?
Stop taking Synaptril and call your doctor if you have a reaction. Call 911 for trouble breathing, swelling of the lips or throat, or fainting.
Stopping is simple: the label gives no tapering rule, and no line is known to cause withdrawal.
Then report it. FDA asks people to report serious reactions through the Safety Reporting Portal at safetyreporting.hhs.gov; partial details still help (FDA, Report a Supplement Problem). The order desk at +1 (323) 348-1373 should hear about it too, along with your order ID.
Stop the capsules
Do not take another until you know the cause.
Call your doctor
Bring the bottle and a list of your medicines.
Report it to FDA
Hives, wheezing, a racing heart and yellow skin all count as serious (FDA, Report a Supplement Problem).
Brain supplements08
Are brain supplements safe in general?
Brain supplements are not checked for safety before they are sold, so none is safe by default. FDA does not approve supplements before they reach the market (FDA, Using Dietary Supplements).
"Natural" does not mean safe, and some products have contained hidden prescription drugs (NCCIH, Using Supplements Wisely). Seals from testing groups do not guarantee safety either (NIH ODS, Supplements: What You Need to Know).
A fully listed label like Synaptril's lets your doctor see every line. Read how we weighed the seller on is Synaptril legit?.
FAQ09
Synaptril safety questions
Can Synaptril cause diarrhea?
It can, mostly because of the magnesium. Too much supplement magnesium causes diarrhea, sometimes with cramps (NIH ODS, Magnesium). One capsule holds 80 mg, below the 350 mg daily limit, so loose stools usually mean you are also taking an antacid, laxative or other magnesium product.
What helps if Synaptril upsets my stomach?
Take the capsule with a meal instead of on an empty stomach, and drink a full glass of water. If nausea or cramps continue after a few days, stop and talk to your doctor. Do not split the dose across the day, since the label gives one capsule daily.
How soon could liver problems from turmeric show up?
Reported turmeric liver injury usually starts 1 to 4 months after someone begins taking it, sometimes later (NIH LiverTox, Turmeric). Watch for yellow skin or eyes, dark urine, unusual tiredness and poor appetite. Stop the capsules and call your doctor if you see any of them.
Can Synaptril cause insomnia?
Possibly, in a few people. Coenzyme Q10 is linked to mild sleep trouble (NCCIH, Coenzyme Q10), although the label lists no stimulant. If you sleep worse after starting, take the capsule in the morning. If that does not help, stop and see whether your sleep recovers.
Is it safe to stop taking Synaptril suddenly?
Yes. The label gives no tapering schedule, and none of the six ingredients is known to cause withdrawal. You can simply stop. If you stopped because of a reaction, tell your doctor and keep the bottle so they can read the label.
Who should I tell first about a Synaptril reaction?
Your doctor, or 911 if you have trouble breathing, throat swelling or fainting. After that, report it to FDA and tell the order desk at +1 (323) 348-1373 with your order ID. Our website inbox cannot see orders.
How do I report a Synaptril reaction to the FDA?
Use FDA's Safety Reporting Portal at safetyreporting.hhs.gov. Add the product name, any codes printed on the bottle, what happened and when. FDA says partial information still helps (FDA, Report a Supplement Problem), so file even if you do not know every detail.
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 an American Synaptril authorized shop, not by the manufacturer or the distributor. We earn money when you buy through our order links.
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