12 Bottles of Fierce Immunity12 Bottles of Fierce Immunity12 Bottles of Fierce Immunity12 Bottles of Fierce Immunity12 Bottles of Fierce Immunity
12 Bottles of Fierce Immunity
12 Bottles of Fierce Immunity
12 Bottles of Fierce Immunity
12 Bottles of Fierce Immunity
12 Bottles of Fierce Immunity

12 Bottles of Fierce Immunity

Grab life by the mane with Rebel Lion Fierce Immunity. Our breakthrough formula is designed to deliver superior bioactive compounds to support your immune system.
Unique synergy of ingredients
Formulated by like-minded scientists
Non-GMO, gluten-free, and third-party tested for purity

12 Bottles of Fierce Immunity


Our Fierce Customers

See why our customers love Fierce Immunity.



Each element is carefully chosen to work in concert. Fierce Immunity is
an unprecedented combination you won’t find anywhere else.

vitamin d

Vitamin D is obtained from sun exposure, foods, and supplements. These sources supply vitamin D in a biologically inactive form. When activating vitamin D, the liver and the kidney transform the inactive form into the physiologically active form, known as calcitriol.

Fierce Immunity is designed to help activate vitamin D and increase calcitriol production. And, unlike other vitamin D supplements, the addition of quercetin can help increase the bioavailability of vitamin D, and arginine can help increase its efficacy.

The correlation between a Th1/Th2 cytokines imbalance and vitamin D level in patients with early chronic obstructive pulmonary disease (COPD), based on screening results (link).

Vitamin D Regulation of Immune Function (link).

The influence of vitamin D on M1 and M2 macrophages in patients with Crohn's disease (

Zinc Ascorbate

Zinc ascorbate is the zinc salt of vitamin C. It has superoxide dismutase-like and antibacterial activity. The combination of zinc and vitamin C supports the innate immune system only when consumed in moderate amounts. Too much zinc weakens, rather than strengthens, the innate immune system.

This function can help increase the efficacy of quercetin and hesperidin, as well as the immune-supporting power of Fierce Immunity.

Clinical efficacy of zinc supplementation in improving antioxidant defense system: A comprehensive systematic review and time-response meta-analysis of controlled clinical trials (link).

Zinc supplementation reduces Candida infections in pediatric intensive care unit: a randomized placebo-controlled clinical trial (link).

Inflammatory response under zinc deficiency is exacerbated by dysfunction of the T helper type 2 lymphocyte-M2 macrophage pathway (link).


Quercetin, a flavonol found in many fruits and vegetables, not only kills bacteria and viruses, but also supports the immune system by increasing the production of immune effector cells. Combined with hesperidin, quercetin can help protect memory functions and slow cognitive decline. 

Since quercetin also can increase the oral bioavailability of vitamin D and support its activation, it can help increase the protective power of vitamin D. Additionally, quercetin can help regulate overproduction of nitric oxide from the I-arginine in Fierce Immunity.

Modulation of Th1/Th2 Cytokine Balance by Quercetin In Vitro (link).

Quercetin, Inflammation and Immunity (link).

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action (link).

Influence of the Neuroprotective Properties of Quercetin on Regeneration and Functional Recovery of the Nervous System (link).

Regulatory Effects of Quercetin on M1/M2 Macrophage Polarization and Oxidative/Antioxidative Balance (


Hesperidin, a flavanone contained in citrus fruits, is a time-honored herbal medicine that was first isolated in 1828. By reducing viral replication, it helps protect against influenza. Hesperidin can reduce inflammation, support the production of immune effector cells, and more.

The safety of hesperidin was confirmed by FASEB (Federation of American Societies of Experimental Biology) upon request of the FDA. Toxicity studies have confirmed the high safety profile of hesperidin after oral intake.

FDA GRAS notices for hesperidin (link).

ChEBI: Hesperidin (link).

Experimental immunology - Differential effect of hesperidin on Th1, Th2, Th17, and proinflammatory cytokines production from splenocyte of Schistosoma mansoni-infected mice (link).

Hesperidin as a Neuroprotective Agent: A Review of Animal and Clinical Evidence (link).

Hesperidin inhibits synovial cell inflammation and macrophage polarization through suppression of the PI3K/AKT pathway in complete Freund's adjuvant-induced arthritis in mice (link).

Orange juice and hesperidin promote differential innate immune response in macrophages ex vivo (link).


L-arginine serves as a building block for proteins and plays an essential role in the immune and cardiovascular systems. This amino acid is essential to nitric oxide production in the body, which can improve blood flow and heart health.

L-arginine can increase the activation of vitamin D, which is designed to help increase the ability of Fierce Immunity to unlock the immune system’s full potential.

Intravenous arginine administration benefits CD4+ T-cell homeostasis and attenuates liver inflammation in mice with polymicrobial sepsis (link).

Arginine-dependent immune responses (link).

Effect of L-arginine on immune function: a meta-analysis (link).

Functional characterization of nutraceuticals using spectral clustering: Centrality of caveolae-mediated endocytosis for management of nitric oxide and vitamin D deficiencies and atherosclerosis (link).


As a mother of four young boys, a business owner, and an elected official with a full-time career - I got sick OFTEN!! I travel a lot for work and found myself getting sick after each business trip. I started Fierce Immunity a few months back and I have not been ill since. A few times I felt a little sickness coming on, but I took my 3 "Fierce Immunity Super-Power Pills" (as I affectionately call them now) and BOOM! - Healthy as a horse again! I tell everyone about these super pills, and I NEVER travel without them!


When I first got a bottle of Fierce Immunity, I didn't expect to tangibly experience a noticeable physical state of improvement. But sure enough I have! Every day I take it, I feel great about an hour afterwards. It’s quite impressive considering it’s something I'd take anyways to boost my immunity. It’s so cool to understand the formulation and how the ingredients are synergistic. Great work Rebel Lion!


When I started taking Fierce Immunity, I was not feeling my best. I noticed after a couple of days I began to feel much better. I spaced them out throughout the day and literally within the hour, I felt my energy levels were higher and felt more alert. Usually with supplements, I don’t really know if they’re working, but with Fierce Immunity, I can genuinely feel the differencein my energy. I’ve now made Fierce Immunity my go-to immunity protector.


I personally felt energized and loved the feeling that I got when I took Fierce Immunity. My kids got sick, and I didn’t while I was taking it! I feel like I am fully protected with Fierce. A big win for me and my family!


My experience with Fierce Immunity was nothing short of miraculous. I was not feeling well, had cold and long Covid symptoms, when I started taking it and by the first week of taking it I was beyond 100% back. My energy was totally restored. It’s interesting because I haven’t felt 100% in a while, and it wasn’t long before I started feeling like myself again. My skin was radiant. I felt vital and my life force was fully back. I’m also a teacher and am around kids who are often sick with colds and viruses, which normally affects me. But with my Fierce, I didn’t get so much as a sniffle!



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