Gammaked, Gamunex-C, and two Yimmugo lots were voluntarily withdrawn after FDA reported a higher rate of allergic/hypersensitivity-type reactions, some medically significant.

Four immune-globulin lots were voluntarily withdrawn by their manufacturers in August 2026 after a higher rate of allergic/hypersensitivity-type reactions, according to an FDA biologics safety update dated August 14.

The newly relevant lots are Gammaked B13K127733, Gamunex-C B23L053203, Yimmugo C795145, and Yimmugo C795165. FDA says some of the reactions associated with the affected immune globulin lots were considered medically significant. [1]

The central safety message is deliberately narrow: this is a confirmed, lot-specific withdrawal action—not evidence that immune globulin as an entire therapeutic class has suddenly become more dangerous.

Hypersensitivity and anaphylactic/anaphylactoid reactions are already recognized risks of immune globulin products. What is new is FDA's identification of a higher reaction rate associated with specific lots and the manufacturers' subsequent withdrawal of those lots. [1]

Which Immune Globulin Lots Were Withdrawn in August?

FDA's August 14 page lists four withdrawals dated August 11 or August 13, 2026.

These four August entries appear at the end of an FDA table that also contains immune-globulin lots withdrawn during 2025. The older entries should not be presented as part of the new August 2026 event. [1]

FDA describes the withdrawals as a precautionary measure taken by the manufacturers because of a higher rate of allergic/hypersensitivity-type reactions.

This wording is important. FDA itself did not physically recall or withdraw the lots; the manufacturers voluntarily withdrew them, and FDA is communicating the safety action.

What Does FDA Mean by a Higher Reaction Rate?

The August notice goes beyond simply saying that more adverse-event reports appeared in a database.

FDA states that the affected lots were voluntarily withdrawn because of a higher rate of allergic or hypersensitivity-type reactions and that some reactions were medically significant. [1]

That should be distinguished from a raw increase in spontaneous adverse-event reports.

Spontaneous-reporting systems such as FAERS are valuable for detecting safety signals, but report counts alone do not establish incidence because the number of exposed patients is generally unknown and reporting can be affected by duplication, under-reporting, publicity, and other biases.

MedicalToxic's What Is FAERS and Why It Matters in Medical Toxicology explains why spontaneous adverse-event counts should not automatically be converted into rates, incidence estimates, or proof of causality.

The August FDA communication is therefore more appropriately described as a regulator-confirmed lot-specific safety action following a higher reaction rate, rather than merely an observation that a database received more reports.

At the same time, FDA's public page does not provide the numerator, denominator, numerical reaction rate, statistical method, or a lot-by-lot comparison with unaffected product. [1]

The magnitude of the increase therefore cannot be calculated from the public notice.

This Is Not a Class-Wide Immune Globulin Warning

The most important risk-communication safeguard is to avoid turning the four lot withdrawals into a class-wide claim.

FDA specifically identifies individual lots. The notice does not say that all Gammaked, all Gamunex-C, all Yimmugo, or all intravenous or subcutaneous immune-globulin products have been withdrawn.

Nor does the August communication announce a new class-wide contraindication or state that immune globulin overall now carries a newly increased hypersensitivity risk.

Instead, FDA explicitly notes that hypersensitivity and anaphylactic/anaphylactoid reactions are already known risks associated with immune globulin products. [1]

The new safety issue is the higher rate associated with specified lots.

For clinicians, pharmacists, infusion centers, hospitals, and patients, this makes the lot number—not simply the product name—the critical identifier.

Why Hypersensitivity Reactions Matter Clinically

Allergic and hypersensitivity reactions to infused biologic products can range in clinical significance, and FDA says some reactions associated with the withdrawn immune-globulin lots were medically significant.

However, the August 14 page does not publish detailed case narratives or provide a breakdown of the symptoms, severity grades, treatments, hospitalizations, or outcomes associated specifically with the four August 2026 lots. [1]

Those details should therefore not be inferred or imported from older immune-globulin safety reports.

FDA does confirm that hypersensitivity and anaphylactic/anaphylactoid reactions are established risks with immune globulin products. [1]

The clinical relevance of the new action lies in identifying product from the affected lots before further administration rather than assuming that a familiar immune-globulin brand is unaffected simply because patients may have previously tolerated it.

FDA's Earlier Immune Globulin Signal Provides Important Context

This is not the first FDA communication involving lot-specific hypersensitivity concerns with immune globulin.

On October 28, 2025, FDA reported that FAERS had received increased reporting of allergic/hypersensitivity-type reactions following infusion of specific Asceniv and Bivigam lots. Some of those earlier reports involved severe events requiring epinephrine, steroids, emergency-department evaluation, or hospitalization. [2]

At that stage, FDA described an active investigation and recommended that healthcare facilities examine their stock and cease use of the affected Asceniv and Bivigam lots.

MedicalToxic covered that earlier phase in Weekly Safety Pulse: FAERS & Recalls.

The distinction between the two stages is useful.

The October 2025 communication explicitly centered on increased FAERS reporting involving particular lots. [2]

The August 2026 page, by contrast, documents voluntary manufacturer withdrawals and characterizes the affected lots as having a higher rate of allergic/hypersensitivity reactions. [1]

The new story is therefore not simply a repetition of the earlier FAERS signal.

What Hospitals, Pharmacies, and Infusion Centers Should Do

FDA gives three direct recommendations for facilities that may hold affected product.

First, healthcare facilities should examine their stock immediately to determine whether they have vials from any affected lot.

Second, FDA says use of product from the listed lots should cease immediately.

Third, affected product should be returned to the point of purchase for replacement. [1]

For the August 2026 update, that means inventory systems should specifically search for:

• Gammaked lot B13K127733

• Gamunex-C lot B23L053203

• Yimmugo lot C795145

• Yimmugo lot C795165

A product-name-only alert is less useful than a lot-specific inventory check because the FDA action does not encompass every lot of these products.

What Patients Should Know

Patients receiving immune globulin should not interpret this announcement as evidence that all immune-globulin therapy is unsafe.

The FDA action applies to the identified lots.

Patients who receive immune globulin through a hospital, infusion center, specialty pharmacy, or home-infusion service can contact their treating team or dispensing provider if they are concerned about whether their product came from an affected lot.

The public FDA communication does not advise patients to discontinue all immune-globulin treatment across the class. [1]

Unnecessary interruption of therapy based solely on the product's brand name would therefore go beyond the scope of the FDA's lot-specific action.

What Is Genuinely New?

The genuinely new development is the addition of four August 2026 immune-globulin lot withdrawals to FDA's current safety page.

Two were withdrawn on August 11:

• Gammaked B13K127733

• Gamunex-C B23L053203

Two Yimmugo lots were withdrawn on August 13:

• C795145

• C795165. [1]

FDA's page, dated August 14, attributes the voluntary withdrawals to a higher rate of allergic/hypersensitivity-type reactions, with some considered medically significant.

That is the current news event.

The known possibility of hypersensitivity with immune globulin is not itself new, and the earlier 2025 FAERS signal involving Asceniv and Bivigam should remain clearly separated from the four August 2026 lots. [2]

Limitations and Remaining Unknowns

FDA's public August 14 communication leaves several important questions unanswered.

The agency does not publish the number of reactions linked to each of the four August lots, the number of patients exposed, the numerical reaction rate, or the degree by which the rate exceeded the expected background.

It also does not provide detailed clinical descriptions of the August cases, identify a confirmed manufacturing mechanism, or state in the public notice why those particular lots had a higher reaction rate.

The page should therefore not be used to calculate incidence, compare the relative safety of Gammaked, Gamunex-C, and Yimmugo, or infer that one manufacturer or immune-globulin formulation is broadly riskier than another.

The evidence supports a narrower conclusion: the specified lots had a sufficiently concerning higher rate of allergic/hypersensitivity-type reactions for their manufacturers to withdraw them as a precautionary safety measure. [1]

Conclusion

FDA's August 14 update identifies four new immune-globulin lots that were voluntarily withdrawn following a higher rate of allergic/hypersensitivity-type reactions.

The immediate action is highly specific: healthcare facilities should identify Gammaked B13K127733, Gamunex-C B23L053203, Yimmugo C795145, and Yimmugo C795165, cease using affected stock, and return it for replacement. [1]

The wider interpretation should remain equally precise.

This is a confirmed lot-specific safety action involving a higher reaction rate, not evidence of a newly demonstrated class-wide increase in immune-globulin hypersensitivity risk. It also should not be reduced to a raw FAERS count: the current FDA communication documents actual voluntary lot withdrawals.

For clinicians and medication-safety teams, the practical priority is therefore straightforward—verify the lot, remove affected stock, and avoid generalizing the warning beyond the products FDA actually identified.

References

1. U.S. Food and Drug Administration. (2026, August 14). Voluntary Lot Withdrawals of Immune Globulin Intravenous (IGIV) and Immune Globulin Subcutaneous (IGSC) for Increased Reports of Allergic/Hypersensitivity Reactions.

2. U.S. Food and Drug Administration. (2025, October 28). Immune Globulin Intravenous (IGIV) and/or Immune Globulin Subcutaneous (IGSC) Lots with Increased Reports of Allergic/Hypersensitivity Reactions.