Drug & supplement interaction

L-cysteine + Insulin Lispro-Aabc

Insulin Lispro-Aabc brand name: Lyumjev.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

L-cysteine has a moderate interaction with Insulin Lispro-Aabc. Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

L-cysteine and Insulin Lispro-Aabc

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIDIABETES DRUGS

Why this applies to Insulin Lispro-Aabc

Insulin Lispro-Aabc falls under ANTIDIABETES DRUGS — the group L-cysteine interacts with.

Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research suggests that L-cysteine can have hypoglycemic effects.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Lyumjev (insulin lispro-aabc) is a fast-acting mealtime insulin that lowers your blood sugar. The concern here is simply that L-cysteine may nudge blood sugar a little lower on its own. If that happens while you are also dosing insulin, the two could add up and push you into a low (hypoglycemia).

I want to be honest about the evidence though: this is based only on animal studies, so it is very much a theoretical caution, not something proven in people. Still, with insulin you already watch for lows. If you start L-cysteine, just keep an eye out for shakiness, sweating, dizziness, fast heartbeat, or confusion, and check your sugar a bit more often. Don't change your insulin dose on your own. Loop in your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lee S, Han KH, Nakamura Y, et al. Dietary L-cysteine improves the antioxidative potential and lipid metabolism in rats fed a normal diet. Biosci Biotechnol Biochem 2013;77(7):1430-4.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

L-cysteine Also Interacts With Other Medications

L-cysteine has 85 moderate known drug interactions in our database — the Insulin Lispro-Aabc one above is one of them. If you take anything else, check it against the full list below.

Moderate 85 No known interaction 2,745 (incl. Insulin Lispro-Aabc)
Taking anything else?

Check Another of Your Medications Against L-cysteine

Covers the 2,830 medications we’ve checked against L-cysteine. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Insulin Lispro-Aabc

This page covers L-cysteine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin Lispro-Aabc page lists 239 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate), Agaricus Mushroom (moderate) and Agmatine (moderate).

By severity: 1 major · 208 moderate · 30 minor.

From our pharmacist’s overview on the Insulin Lispro-Aabc page

“Lyumjev (insulin lispro-aabc) is an ultra rapid mealtime insulin, built to drop blood sugar quickly, which is why its 239 interacting supplements call for genuine care. Nearly all of them work on the same axis.”

Reviewed by 2 · Jul 18, 2026

Open the Insulin Lispro-Aabc interaction page

One more smart check

Taking L-cysteine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1 real supplement products containing L-cysteine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-cysteine. Your product may carry other ingredients that interact with Insulin Lispro-Aabc too, on top of L-cysteine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where L-cysteine and Insulin Lispro-Aabc Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement L-cysteine
Steady interest

#812 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Insulin Lispro-Aabc
Steady interest

#2,426 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About L-cysteine

What is L-cysteine?

  • Antioxidant support
  • Skin and hair health
  • Liver support
  • Respiratory and mucus thinning
  • General protein/amino acid supplementation

L-cysteine is a sulfur-containing amino acid your body uses to make proteins and the antioxidant glutathione. Most people get enough from food, and supplements are usually well tolerated, but strong evidence supporting specific health benefits from extra L-cysteine is limited. Talk to your pharmacist or doctor before starting it, especially if you are pregnant, breastfeeding, or have a health condition.

Read the full L-cysteine monograph & all interactions
Keep checking

Other Drugs & L-cysteine

Browse every other medication we’ve checked against L-cysteine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
85Moderate
0Minor
2,744No known interaction
85 Moderate 2,744 No interaction
Moderate

85 interactions

Showing 60 of 85 moderate interactions — see all 85 on the L-cysteine page.

No interaction 2,744 drugs checked — show the list

We also checked L-cysteine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,744 medications checked with no known interaction — see the full L-cysteine list.

See the full L-cysteine interactions page
See every supplement checked against Insulin Lispro-Aabc, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
L-cysteine monograph › Uses, safety, and every drug interaction in one place Insulin Lispro-Aabc supplement interactions › Every supplement checked against Insulin Lispro-Aabc, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking L-cysteine and Insulin Lispro-Aabc Together: Common Questions

Can you take L-cysteine with Insulin Lispro-Aabc?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the L-cysteine and Insulin Lispro-Aabc interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Insulin Lispro-Aabc and L-cysteine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.