What is the most common thymosin alpha-1 dose in published studies?

The most recognizable chronic-study dose is 1.6 mg subcutaneously twice weekly. A randomized hepatitis B trial used that amount for 26 or 52 weeks. It is a research protocol, not a universal prescription: vaccine studies sometimes used body-surface-area dosing, while hospital sepsis studies tested much more frequent schedules.

How often was thymalfasin given in hepatitis trials?

Twice weekly was the common pattern in chronic hepatitis trials. In a 1998 randomized hepatitis B study, investigators used 1.6 mg subcutaneously twice weekly for either 26 or 52 weeks. That frequency reflects the protocol and disease studied; it does not show that the same timing is appropriate for an unrelated immune condition.

How long does a thymosin alpha-1 protocol last?

Duration depends on the research setting. The cited hepatitis trial used 26 or 52 weeks, an influenza-vaccine study used eight doses, and major sepsis trials used only seven days under hospital care. A prescriber needs a condition-specific rationale and a defined point for reassessment rather than choosing duration from the size of a vial.

Why did sepsis trials use thymosin alpha-1 more often?

They were testing short-term immune modulation during an acute critical illness. ETASS used twice-daily dosing for five days followed by once daily for two days, while TESTS used every 12 hours for seven days. Those were closely monitored hospital protocols, and the large TESTS trial found no conclusive reduction in 28-day mortality.

Does thymosin alpha-1 have U.S. approval?

No. The FDA has not approved a thymosin alpha-1 drug product in the United States. Thymalfasin has approvals for certain uses in other countries, while Promise offers a patient-specific compounded formulation. Its regulatory status is one input to care, and the decision to prescribe remains between the patient and a licensed provider.

Who decides the dose for compounded thymosin alpha-1?

The prescribing provider sets the patient-specific amount, frequency and duration, and the dispensing pharmacy label states the directions and concentration. The provider weighs the intended use, health history, immune conditions, other medicines, relevant laboratory monitoring and the quality of evidence. A schedule copied from a trial or online chart leaves out those decisions.

Thymosin Alpha-1 Dosage: What Trials Used

Thymosin alpha-1 dosage is not one universal number. In the chronic hepatitis B trials that established the familiar pattern, thymalfasin was given subcutaneously at 1.6 mg twice weekly for 26 or 52 weeks. Acute sepsis trials used much more frequent hospital regimens, including every 12 hours for seven days. Those schedules are study designs, not instructions for self-treatment. In the United States, there is no approved dosing label for thymalfasin; a prescriber has to weigh the reason for treatment, evidence, health history, other medicines, formulation and monitoring before setting an individual plan.

For the molecule and immune-signaling background, see what thymosin alpha-1 is.

What thymosin alpha-1 dosage trials actually used

The published literature does not support a single schedule across every proposed use. It supports a set of protocols built for different questions.

Research setting	Protocol reported in the study	Duration	What the protocol tells us
Chronic hepatitis B	1.6 mg subcutaneously twice weekly	26 or 52 weeks	This is the source of the familiar chronic-use pattern
Influenza-vaccine adjunct in older men	900 mcg/m² subcutaneously twice weekly	Eight doses	Some early work used body-surface-area dosing rather than a fixed dose
Severe sepsis, ETASS	1.6 mg subcutaneously twice daily for five days, then once daily for two days	Seven days	Acute inpatient research used a denser schedule
Sepsis, TESTS phase 3	1.6 mg subcutaneously every 12 hours	Up to seven days	A modern large trial tested frequent short-term dosing under ICU care

The hepatitis B figures come from a 98-person randomized trial published in Hepatology in 1998. Participants received 1.6 mg twice weekly for either 26 or 52 weeks, while a third group received no specific treatment (Chien et al., Hepatology 1998). That trial reported its own disease-specific outcomes; it did not establish a general immune-support dose.

The older vaccine-adjuvant study was different again. Ninety men ages 65 to 99 were randomized to thymosin alpha-1 or placebo alongside influenza vaccination, using 900 mcg/m² twice weekly for eight doses (Gravenstein et al., Journal of the American Geriatrics Society 1989). A body-surface-area protocol from one older study cannot be cleanly converted into a universal fixed dose.

Why twice-weekly dosing became the familiar pattern

Twice weekly became recognizable because it was repeatedly used in chronic viral-hepatitis development, not because every thymosin alpha-1 question points to that interval. The peptide's measured serum half-life is only about 1.5 to two hours, yet chronic protocols spaced injections several days apart. That tells us the schedule was empirical: investigators were testing downstream immune effects rather than trying to keep a constant blood concentration.

It also explains why changing frequency is a clinical decision. Dividing the same weekly amount into smaller injections is not automatically equivalent. Neither is borrowing an every-12-hour ICU protocol for outpatient use. Frequency, total exposure and the condition being studied all change together.

Duration follows the indication, not the vial

The hepatitis B trial ran for six months or a full year. The vaccine study covered eight doses. Sepsis protocols compressed treatment into seven days because they were studying an acute, life-threatening hospital condition alongside standard critical care.

The large TESTS trial makes the limits especially clear. It randomized 1,106 adults with sepsis to thymosin alpha-1 or placebo, used 1.6 mg every 12 hours for seven days, and found 28-day mortality of 23.4% versus 24.1%; the corrected hazard ratio was 0.97 with a 95% confidence interval of 0.76 to 1.24 (Wu et al., BMJ 2025). The authors found no conclusive evidence of lower 28-day mortality. A higher-frequency research protocol is therefore evidence of what was tested, not proof that more frequent dosing works better.

What a prescriber weighs

A thymalfasin dosage decision starts with the reason it is being considered. A prescriber then has to separate a protocol supported by human data from one extrapolated across unrelated conditions. Other factors include:

whether the intended use resembles the population in a published study;
immune or autoimmune conditions, active infection and transplant history;
medicines that suppress or alter immune activity;
kidney and liver function and the laboratory markers relevant to the condition;
the exact concentration and directions supplied by the compounding pharmacy; and
whether the planned duration has a defined endpoint for reassessment.

This is why a dose copied from a trial table is incomplete. It leaves out eligibility, formulation, monitoring, stopping criteria and the evidence behind the indication.

U.S. approval and compounding status

Thymalfasin has been approved for certain uses in a number of countries outside the United States and has been studied in hepatitis B, sepsis and as a vaccine adjunct. Promise's thymosin alpha-1 is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved. Compounded medications are not reviewed by the FDA for safety, effectiveness or quality before dispensing (FDA's thymosin alpha-1 evaluation).

The regulatory date is worth getting right. The FDA's Pharmacy Compounding Advisory Committee reviewed thymosin alpha-1 free base and acetate on December 4, 2024, not at its July 2026 meeting. The committee voted 4-17 against recommending either form for the 503A Bulks List (FDA summary minutes). The official July 23-24, 2026 agenda covered seven other peptide groups. Advisory-committee votes are recommendations, and further agency action proceeds through its regulatory process.

A licensed provider may still prescribe a compounded formulation when they judge it appropriate; that decision is between the patient and the doctor. Regulatory status should be part of that conversation, not a substitute for it. How compounded medications are made explains the pharmacy side of the distinction.

How the Promise process fits

At Promise, a licensed provider reviews every request, and not everyone qualifies. If a prescription is written, a licensed U.S. compounding pharmacy prepares and dispenses the medication with patient-specific directions. The concentration and label attached to that prescription control; numbers from a hepatitis or sepsis paper do not.

That accountability is the useful dividing line between prescribed care and a vial sold online without clinical review. How to get prescribed peptides walks through the intake, provider review, pharmacy and follow-up sequence.

The useful question is not just “how much?”

A sound plan has four linked parts: amount, frequency, duration and a reason to reassess. Published thymosin alpha-1 schedules range from twice weekly for months to twice daily for days because they were designed for different conditions in different settings. The dose only makes sense when those other parts travel with it.