Customer Ratings & Reviews

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4.7

Based on 23,357 ratings

18,852

3,064

1,036

200

205

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What customers say

Customers highly praise the Doctor's Best Fully Active B Complex for its excellent quality, clear ingredients, and effectiveness in improving energy levels, sleep quality, and overall well-being. Many appreciate the inclusion of Quatrefolic for better absorption and utilization of folate. The product is noted for its easy-to-swallow capsules with no aftertaste and convenient packaging. Some users experienced a mild niacin flush initially but found it manageable. Long-term users report consistent benefits, making it an essential supplement in their routine. The brand's reliability and quick delivery through iHerb are also frequently mentioned positives.

Review highlights

Top positive review

iHerb customer

Posted on Sep 19, 2024

Singapore

Excellent B complex!

This B complex is really good, this was my N times repurchased. A must have supplement, it improve my energy and mood. But Wonder if anyone else facing the same issue. The weather in SG accelerates the oxidation of health supplement, which is really troubling. Well, my home doesn't get direct sunlight and is well-ventilated. Really hope can solve this problem.

(23,047)

iHerb customer

Silver

Posted on Oct 27, 2025

Thailand

170

Good

Verified purchase

I’ve been taking this supplement for a while. The quality seems good, and it’s easy to take with no noticeable side effects. I haven’t seen dramatic results yet, but everyone’s body is different. Overall, it’s a decent, reliable option for general health support.

iHerb customer

Posted on Sep 7, 2025

Thailand

Great for stress

Verified purchase

A Fully Active B-Complex with Quatrefolic® is a type of B vitamin supplement designed to provide the body with highly bioavailable forms of all the essential B vitamins. Unlike standard B-complex products that often contain cheaper, less absorbable forms, a “fully active” formula uses the body-ready versions of each vitamin—for example, methylcobalamin instead of cyanocobalamin for B12, and pyridoxal-5’-phosphate instead of pyridoxine for B6. One of the key ingredients, Quatrefolic®, is a patented form of 5-MTHF (5-methyltetrahydrofolate), the active form of folate. This is especially important because some people have genetic variations (like MTHFR mutations) that limit their ability to convert synthetic folic acid into its usable form. By supplying folate as Quatrefolic®, the supplement bypasses this step and provides folate that can be immediately used by the body for critical processes such as red blood cell formation, DNA synthesis, and neurotransmitter production. A Fully Active B-Complex with Quatrefolic® is often taken to support energy production, nervous system health, stress resilience, cardiovascular wellness, and overall metabolic function. Because B vitamins are water-soluble and not stored in large amounts, they need to be replenished regularly through diet or supplementation. This type of supplement is generally considered safe, but taking it in very high doses may cause imbalances or side effects, so it’s best used under guidance from a healthcare professional.

Tbeaton23

Silver

Posted on Jan 8, 2026

United States

179

B-Complex For Gym

Verified purchase

Doctors best is a great company once again with a solid product, this will give you energy and help with mood. I take it pre workout sometimes and it helps with energy. There is no niacin flush and the size of the pills are not large. Great packaging by doctors best again.

Jhene

Posted on Oct 31, 2025

United Kingdom (UK)

All Day Energy

Verified purchase

You want to get energised without taking coffee or energy drinks? This is for you. This is super amazing, and you only need 1 capsule daily. Love taking it! Right amount of each vitamins. Worth every penny.

iHerb customer

Posted on Nov 4, 2025

Jordan

Excellent Quality Supplements — I Can Feel the Difference!

Verified purchase

I’ve been taking these supplements for a few weeks, and I can honestly say they’ve made a noticeable difference in my energy and overall well-being. The quality is excellent — the capsules are easy to swallow and gentle on the stomach. I appreciate that they contain clean ingredients with no artificial fillers. The packaging is sturdy, and the product arrived fresh and well-sealed. I also love that iHerb ships quickly and always provides authentic, high-quality products. Definitely worth the purchase — I’ll keep buying this regularly!

iHerb customer

Posted on Sep 25, 2025

Romania

High Quality B Complex with Active Ingredients

Verified purchase

This Doctor’s Best Fully Active B Complex impressed me with its quality. The ingredients are well chosen, especially the active forms of B vitamins for better absorption. The dosage is just right at one capsule a day, making it easy to take consistently. The size of the bottle (60 veggie caps) is convenient and lasts a good while. Benefits include noticeable support for energy and metabolism. Since these are capsules, there’s no taste, which is a plus for me.

iHerb customer

Posted on Aug 31, 2025

Singapore

Great supplement

Verified purchase

I started taking Fully Active B-Complex for energy and stress support. Within a week, I felt more alert and less mentally drained. It gave a clean, natural boost without any jitters. Also helped improve my mood and focus. Easy on the stomach and no weird aftertaste. A great daily supplement for energy and overall wellness.

iHerb customer

Posted on Sep 19, 2024

Singapore

Excellent B complex!

Verified purchase

iHerb customer

Posted on Apr 12, 2026

Sweden

good product

Verified purchase

I've been using this B complex for about two months now and I'm genuinely impressed with the quality. What sets it apart is the use of bioavailable, active forms — methylcobalamin instead of cyanocobalamin, methylfolate (Quatrefolic®) instead of folic acid, and riboflavin-5-phosphate instead of plain riboflavin. This matters a lot, especially for people who have MTHFR gene variants and can't properly convert synthetic folate.

iHerb customer

Posted on Apr 11, 2026

Ghana

Excellent product

Verified purchase

I am already starting to see the effects this is a really good b complex vitamins I am so impressed I will definitely order again when I run out of it the package is very clean the potency is high and it helps my nervous system and metabolism I am already seeing effect and the taste is mild

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