Herb & supplement monograph

Glycine Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Glycine interacts with medications. The heart of this page is the interaction list — every drug Glycine is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Glycine is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Reviewed by licensed pharmacists Sourced from Natural Medicines

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Glycine Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Glycine drug interaction appears low for most people. Only one interaction is documented, it is rated moderate rather than major, and no other medications are flagged.

Interactions deserving the most attention

The one combination that deserves real attention is clozapine, an antipsychotic used for schizophrenia. A small human study found that adding glycine to clozapine made schizophrenia symptoms worse compared with clozapine alone, so this is more than a theoretical concern, even though the reason for the effect is not clear. Anyone taking clozapine should treat glycine supplements with caution and involve their prescriber, since symptom control on this medication matters a great deal.

What the rest of the list means

Glycine's interaction profile is unusually short for a supplement, which fits with it being one of the body's simplest amino acids. Outside of clozapine, there is no documented signal that glycine changes how other medications work. That said, a short list reflects what has been studied, not a guarantee of zero effect elsewhere.

Check your medications against Glycine

Based on HelloPharmacist’s Glycine interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Glycine

1 medication has a known interaction with Glycine, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Glycine using our pharmacist-reviewed interaction data.

AI summaries are generated from our Glycine interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Glycine combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Glycine affects

Every type of medication (drug category) Glycine is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Glycine interacts with

Clozapine (clozaril)

Clozapine (Clozaril)

Theoretically, glycine might decrease the effectiveness of clozapine.
One small clinical study in patients with schizophrenia shows that adding glycine to clozapine therapy worsens symptoms of schizophrenia when compared with clozapine alone. The mechanism of this interaction is unclear.

Likelihood Probable Evidence B

Monograph

Glycine: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Glycine is a non-essential amino acid your body makes on its own and that also appears in protein-rich foods. It is most studied for improving sleep quality, where early research is promising but limited, and it appears generally well tolerated at common doses. Talk with your pharmacist or doctor before starting it, especially if you take other medicines or have a health condition.

Part used: Amino acid (made synthetically or by the body)
Common forms: Powder, capsules, tablets

People commonly use it for

Sleep quality and insomnia
Relaxation
Cognitive function
Metabolic health
General wellness

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated at typical doses, but long-term safety data are limited.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Glycine is one of the simplest amino acids, the building blocks that make up protein in your body. It is called a non-essential amino acid because your body can make its own supply, so you do not depend entirely on food to get it.

You naturally take in glycine from protein-rich foods such as meat, fish, dairy, beans, and gelatin. As a supplement, it is usually made in a lab and sold as a powder, capsule, or tablet. The powder has a slightly sweet taste, which is one reason it is easy to mix into water.

People most often use glycine supplements for sleep and relaxation, and some take it as part of a general wellness or metabolic-support routine.

How it works

Glycine plays many roles in the body. It is used to build proteins and also helps make important molecules like glutathione (an antioxidant), creatine, and parts of the substance that gives blood its red color.

In the brain and nervous system, glycine acts as a neurotransmitter, a chemical messenger. It can have a calming, signaling role and may also affect body temperature, which is one proposed reason it might help with sleep.

Much of what we know about how glycine works at the cellular level comes from laboratory and animal research. These mechanisms help explain why it is being studied, but they do not by themselves prove it will help any given person.

Effectiveness

Does Glycine work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 18 uses evaluated

1 Possibly effective 17 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Schizophrenia