zstacklife.com

2.8
2.8 Based on 33 reviews

Zelenko Labs, built on the legacy of Dr. Vladimir Zelenko, creates products with purpose, precision, and integrity. Every formulation is made with high-quality ingredients and consistent standards, so you can feel confident in what you’re using. Thoughtfu...

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Average Rating

2.8

/
5

33 Reviews

5 Star
41%
4 Star
6%
3 Star
0%
2 Star
0%
1 Star
53%

All Reviews

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Karen Cardin
My issue was getting " offers" from Capitol One credit cards on my notification emails, I asked abou

My issue was getting " offers" from Capitol One credit cards on my notification emails, I asked about it, its a cookies or 3rd party thing, not Zelenko Labs. I have been using Dr Zelenko's products since the covid debacle, never had a problem. Customer Service was always there to answer any questions, emailed personally, to me, not some "canned" answer. I also order Zstack for my 92 year old mom and my 10 year old grandson....only issue I've ever had was when they had to change the formula for Z-Night (one ingredient moved to needing a prescription), it took a little while, but it was reforulated and back in stock asap. The new formula is just as good as the old one was, half an hour after to taking, Im off to a "gentle" restful sleep !

5
Date of experience: Feb 19, 2026
Karen Cardin
My issue was getting " offers" from…

My issue was getting " offers" from Capitol One credit cards on my notification emails, I asked about it, its a cookies or 3rd party thing, not Zelenko Labs. I have been using Dr Zelenko's products since the covid debacle, never had a problem. Customer Service was always there to answer any questions, emailed personally, to me, not some "canned" answer. I also order Zstack for my 92 year old mom and my 10 year old grandson....only issue I've ever had was when they had to change the formula for Z-Night (one ingredient moved to needing a prescription), it took a little while, but it was reforulated and back in stock asap. The new formula is just as good as the old one was, half an hour after to taking, Im off to a "gentle" restful sleep !

5
Date of experience: Feb 18, 2026
Linda Tucker
Thank you Dr Zelenko

I am very fortunate to have found Dr Zelenko’s vitamins. At 80 years old, I have been able to stay well and have not suffered even one Covid event. I attribute my good health to Dr. Zelenko’s vitamins.

5
Date of experience: Feb 15, 2026
RavenRebel Rebel
I started taking Z-Stack after I got…

I started taking Z-Stack after I got COVID in December 2022. I did not take the jab. I have had zero sick days from January 2023 to date.I don’t see a time that I won’t be taking it.

5
Date of experience: Feb 12, 2026
I had a fast and great response to my…

I had a fast and great response to my issue that was quickly resolved.I am so thankful!Pam

5
Date of experience: Feb 06, 2026
Delicious gummies

I get the kids gummies for my children and end up stealing some for myself

5
Date of experience: Feb 04, 2026
Fern Murphy
Unmatched customer service

We purchsed a large order, which was received within a week. Unfortunately, one bottle contained a capsule that had broken open and spilled its contents into the bottle (that's happened to all of us one time or another.)Upon receipt of photo of product, the company immediatle replaced the entire order. now THAT's great customer service!

5
Date of experience: Feb 03, 2026
Stephy D
Been using Z-Stack and Z-Night

Been using Z-Stack and Z-Night and really like both. Z-Stack feels like solid daily support, and Z-Night helps me relax and sleep better without feeling groggy. Clean formulas, all natural, brand I trust. Would recommend.

5
Date of experience: Jan 15, 2026
henri
Scam/rip off

Zstacklife has been full of contradictions, gaslighting and evasive customer service. They sent my shipment confirmation at 1:16 PM, only a few hours before closing. I didn’t see it until after they were closed, and when I called the next morning, they said it had already shipped and refused to cancel.When I brought up the late confirmation, the rep denied the timing despite the clear timestamp. When I emailed support with the screenshot, they dodged the issue entirely and blamed a credit card problem that wasn’t even relevant. My online account also marked the order as “Ready for pickup,” which is odd for an online-only business.The most concerning part? Instead of addressing my questions or correcting the issue, the company cancelled my subscriptions. A transaction like this is akin to a toddler throwing a tantrum, but a health company to shut down the conversation rather than resolve it is inexcusable. This is extremely toxic, dismissive, and unprofessional.

1
Date of experience: Nov 18, 2025
Kathy
Z-Stack has been a godsend - I'm NEVER sick

I've been taking Z-Stack for close to 4 years and have not been sick one day since I started taking it. I am 72 years old, and full time daycare for a granddaughter in school so the germs do come home, but she also has not been sick since she started taking the Kid's Z-Spike gummies. I DO NOT understand all the bad reviews unless they are bots or angry people in general. I have needed to contact customer service MANY times and always (during business hours) get a live person with NO foreign accent, and they are always more than helpful! For those who are having problems with customer service, perhaps you're calling a wrong number. Their customer service # is 800-935-3656 and I NEVER have an issue with getting a wonderful representative. The product itself is a godsend. Miraculous to NEVER get sick at 72 years old in the 4 years I've been taking it. IGNORE BAD REVIEWS! Not true!

5
Date of experience: Sep 03, 2025

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Business Details

  • Zelenko Labs, built on the legacy of Dr. Vladimir Zelenko, creates products with purpose, precision, and integrity. Every formulation is made with high-quality ingredients and consistent standards, so you can feel confident in what you’re using. Thoughtful, reliable, and principled — Zelenko Labs products are made for people who care about quality.

    Our All American customer service team is here to help Monday through Friday, 9 AM to 5 PM EST — just give us a call at 1-800-ZELENKO (1-800-935-3656) or email our team at support@zstacklife.comSee more

  • email support@zstacklife.com
  • call 18009353656
  • language https://zstacklife.com

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