Drug & supplement interaction

Black Tea + Insulin Glargine Recombinant

Insulin Glargine Recombinant brand name: Toujeo Solostar.

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

Black Tea has a minor interaction with Insulin Glargine Recombinant. Theoretically, taking black tea with antidiabetes drugs might interfere with blood glucose control.

Read the full interaction report
SeverityMinor
LikelihoodUnlikely
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Black Tea and Insulin Glargine Recombinant

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

Minor

ANTIDIABETES DRUGS

Why this applies to Insulin Glargine Recombinant

Insulin Glargine Recombinant falls under ANTIDIABETES DRUGS — the group Black Tea interacts with.

Theoretically, taking black tea with antidiabetes drugs might interfere with blood glucose control.
Black tea contains caffeine. Reports claim that caffeine might increase or decrease blood sugar levels. Also, some evidence in healthy individuals suggests that drinking black tea reduces blood sugar.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the deal with your Toujeo (insulin glargine). This is a long-acting basal insulin that lowers your blood sugar steadily over about 24 hours. The concern with black tea is really about the caffeine, which has a bit of a split personality. Some reports suggest caffeine can nudge blood sugar up, while other studies show black tea itself may slightly lower it. So the effect isn't predictable, and honestly the evidence here is weak and the risk is rated as minor and unlikely.

What this means in practice: an occasional cup or two probably won't move the needle much. But large amounts of strong tea could, in theory, make your numbers a touch harder to read, raising the chance of either a high or a low (shakiness, sweating, lightheadedness). Don't change your insulin dose over this. If you notice your readings drifting after adding tea, just check your glucose more often and mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Watson JM, Jenkins EJ, Hamilton P, et al. Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes. Diabetes Care 2000;23:455-9. PubMed
  2. Bell DG, Jacobs I, Ellerington K. Effect of caffeine and ephedrine ingestion on anaerobic exercise performance. Med Sci Sports Exerc 2001;33:1399-403. PubMed
  3. Bahorun T, Luximon-Ramma A, Neergheen-Bhujun VS, Gunness TK, Googoolye K, Auger C, Crozier A, Aruoma OI. The effect of black tea on risk factors of cardiovascular disease in a normal population. Prev Med. 2012 ;54 Suppl:S98-102. PubMed

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

Black Tea Also Interacts With Other Medications

Black Tea has 8 major, 572 moderate, 113 minor known drug interactions in our database — the Insulin Glargine Recombinant one above is one of them. If you take anything else, check it against the full list below.

Major 8 Moderate 572 Minor 113 No known interaction 2,137 (incl. Insulin Glargine Recombinant)
Taking anything else?

Check Another of Your Medications Against Black Tea

Covers the 2,830 medications we’ve checked against Black Tea. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Insulin Glargine Recombinant

This page covers Black Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin Glargine Recombinant page lists 242 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 2 major · 211 moderate · 29 minor.

From our pharmacist’s overview on the Insulin Glargine Recombinant page

“If you inject insulin glargine (Toujeo Solostar), this list deserves real respect, because all 242 ingredients on it bear on the number you track daily, your blood sugar. Most of the 211 moderate entries add to insulin's glucose-lowering effect and can tip you into hypoglycemia, a dangerous low, while a smaller group pushes sugar upwar…”

Reviewed by 2 · Jul 18, 2026

Open the Insulin Glargine Recombinant interaction page

One more smart check

Taking Black Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 271 real supplement products containing Black Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Tea. Your product may carry other ingredients that interact with Insulin Glargine Recombinant too, on top of Black Tea — 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 Black Tea and Insulin Glargine Recombinant 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 Black Tea
Top 25%

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

29 days ago today
Medication Insulin Glargine Recombinant
Steady interest

#2,071 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 Black Tea

What is Black Tea?

  • Mental alertness and energy
  • Heart health support
  • Blood pressure and cholesterol
  • Digestive complaints
  • Weight management
  • Antioxidant support

Black tea is a popular caffeinated drink made from the fully oxidized leaves of the Camellia sinensis plant, and it contains caffeine and antioxidant plant compounds. Moderate tea drinking is generally safe for most adults and may modestly support heart health and alertness, but it is not a proven treatment for any disease. If you are pregnant, breastfeeding, sensitive to caffeine, or taking medicines, talk to your pharmacist or doctor.

Read the full Black Tea monograph & all interactions
Keep checking

Other Drugs & Black Tea

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

8Major
572Moderate
113Minor
2,136No known interaction
8 Major 572 Moderate 113 Minor 2,136 No interaction
Major

8 interactions

Moderate

572 interactions

Showing 60 of 572 moderate interactions — see all 572 on the Black Tea page.

Minor

113 interactions

Showing 60 of 113 minor interactions — see all 113 on the Black Tea page.

No interaction 2,136 drugs checked — show the list

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

Showing the 60 most looked-up of 2,136 medications checked with no known interaction — see the full Black Tea list.

See the full Black Tea interactions page
See every supplement checked against Insulin Glargine Recombinant, 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
Black Tea monograph › Uses, safety, and every drug interaction in one place Insulin Glargine Recombinant supplement interactions › Every supplement checked against Insulin Glargine Recombinant, 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 Black Tea and Insulin Glargine Recombinant Together: Common Questions

Can you take Black Tea with Insulin Glargine Recombinant?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Black Tea and Insulin Glargine Recombinant interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Insulin Glargine Recombinant and Black Tea?

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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.