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Rated 5 out of 5 stars

I started taking Z Stack shortly after COVID hit. Haven't been sick. Yes, I didn't get COVID either. My immune system is thanking me. I also have started (a few months ago) talking CALM. It's enh... See more

Company replied

Rated 5 out of 5 stars

Thank you so much for the quick response, for the product that is beneficial for our health, and for your help also on sending us the vitamins to our current address. We truly appreciate it and value... See more

Company replied

Rated 5 out of 5 stars

This is my first year since Covid to be and feel healthy even during flue season. The Zelinco Protocol is a wonderful solution for rebuilding your immune system.

Company replied

Rated 5 out of 5 stars

I’ve been using Z stack for going on six years ever since Covid started and it has been my go to immune booster. I use the Z night now to get a restful sleep and they Zelin go laps is my trust is Sour... See more

Company replied

Company details

  1. Vitamin & Supplements Shop
  2. Herbal Medicine Shop

Written by the company

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.com


Contact info

4.5

Excellent

TrustScore 4.5 out of 5

50 reviews

5-star
4-star
3-star
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1-star

Replied to 33% of negative reviews

Typically takes over 1 month to reply

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Rated 5 out of 5 stars

Thank you so much for the quick…

Thank you so much for the quick response, for the product that is beneficial for our health, and for your help also on sending us the vitamins to our current address. We truly appreciate it and value your business.

22 April 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you Giuliana!

Rated 5 out of 5 stars

Z Stack & CALM are fantastic!!

I started taking Z Stack shortly after COVID hit. Haven't been sick. Yes, I didn't get COVID either. My immune system is thanking me.
I also have started (a few months ago) talking CALM. It's enhanced my use of St Johns' Wort and a prescription med for anxiety.
I would recommend both supplements to anyone asking about them.

13 April 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thankyou Marlene!

Rated 5 out of 5 stars

I’ve been using Z stack for going on…

I’ve been using Z stack for going on six years ever since Covid started and it has been my go to immune booster. I use the Z night now to get a restful sleep and they Zelin go laps is my trust is Source for health protection.

29 March 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you Timothy!

Rated 5 out of 5 stars

Zstack is the best supplement ever made

Zstack is the best supplement my husband and I have had so far. We’ve never been sick since we started to use it. It has every ingredient in it that our body needs. Unfortunately we’re paying a postage as high as for one bottle of Zstack. This is the only reason we have to stop buying it. For this reason being said we’re not happy that nothing can be done in that direction. Although we would recommend Zstack to anyone.

25 March 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you so much for your kind words Jordan! We will work on the cost of International Shipping. If you ever stop by, in the USA we have free domestic shipping.

Rated 5 out of 5 stars

You will not be disappointed.

I have had a subscription for Z-Stack for over 4 years. After covid I was looking for a good vitamin. I knew I was low in Vitamin D, and I wanted a vitamin that would help with my low Vitamin D levels. I started listening to Dr. Zelenko and decided to try the Z-Stack. After taking Z-Stack for several months, I had bloodwork done and my Vitamin D levels were better than they ever have been and continue to be at a healthy level every year and that is why I continue my subscription each year. The vitamins work. I am confident these vitamins help me stay healthy. You will not be disappointed with these vitamins.

16 March 2025
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you Juanita, I love to hear stories like yours!

Rated 5 out of 5 stars

Our family has been using Zelenko…

Our family has been using Zelenko products since their inception. My grands especially like the strawberry flavored gummies now ZFlu. Thank you for keeping Dr. Zelenko’s legacy alive and well!

12 March 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you Linda!

Rated 4 out of 5 stars

Z Stack 👍🏻

I use Z Stack & it really helps. Haven’t been sick in over 5 years. I did cancel Z Night because I saw no benefit to me after 2 years.
Over all been quite satisfied. The support staff have been very helpful and supportive.

3 March 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you for your feedback!

Rated 5 out of 5 stars

Zflu is my flu fighter!

I have been using Zflu since Dr.Zelensky developed it. Zflu has all the vitamins/minerals needed to prevent and or treat the flu, without having to spend all the money on each of the vitamins separately. I even have my grandson taking Kids Zflu and have recommended it to all my friends. Zflu keeps us symptom-free all year long!!!

28 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

I LOVE TO HEAR IT!!!!

Rated 5 out of 5 stars

Dr Zalenko's products are top of the…

Dr Zalenko's products are top of the line; my husband and I have been on them since the onset. We have also shared them with family and friends for them to try. We feel our immune system has gotten stronger since we first started with Z-stack and now on Z-detox. I will continue to promote them on facebook and instagram as well because I trust this for everyone.

27 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you!

Rated 5 out of 5 stars

Great service.

I had not gotten my order after 2 weeks time. I was sent a replacement right away. Thank you! Also, this product-Z-Stack has been fantastic in maintaining immune system. I have been taking it for years and have not gotten sick for a long time. No yearly cold or flu like many acquaintances. Highly recommended.

20 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Always a pleasure Lisa!

Rated 5 out of 5 stars

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 reformulated 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 !

17 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Love to hear it Karen!

Rated 5 out of 5 stars

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.

15 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

Thank you Linda!

Rated 5 out of 5 stars

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.

12 February 2026
Unprompted review
ZELENKO LABS logo

Reply from ZELENKO LABS

We love to hear it! Be well!

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