A calf thymus extract meant to restore immune cells a shrinking thymus stops making with age. Soviet-era hospital use and one long follow-up of adults past 60 reported faster recovery, fewer age-related illnesses and lower death rates — almost all from the institute that developed it, and never repeated. Harms are limited and mostly allergic; supply is unverified. (Full Review)

Protocol

Standard course

10 mg daily, intramuscular, 5–10 days

Lyophilised powder reconstituted in 1–2 mL of sterile isotonic saline. Registered adult range 5–20 mg daily, 30–100 mg per course.

Longevity schedule used by the developers

Same course, once or twice yearly

The reported long-term mortality effect came from annually repeated courses over six years, not from continuous dosing.

Single versus split dosing

One injection daily

Every published protocol uses one daily injection; no trial has compared split dosing. Morning injection keeps any injection-site reaction observable through waking hours.

Time to effect

Severe respiratory infection

Within the 5–10 day course

Blood immune and inflammatory markers shifted within the course; the inflammatory phase of severe COVID-19 was shortened.

Mortality & age-related illness

6–8 years

Inferred from year-scale follow-up of annually repeated courses and not perceptible to the individual taking it.

Severe burn wound closure

First graft ~5 days earlier

Hospital stay was about 11 days shorter than in comparison patients in a small, unblinded single-centre series.

Benefits

High: Faster recovery from severe acute respiratory infection

Medium: Lower mortality and fewer age-related illnesses in older adults

Low: Faster wound closure and shorter hospital stay after severe burns; faster resolution of acute suppurative and post-surgical infection; recovery of immune indices after radiation or cancer treatment (conflicted); shorter hospital stay in destructive pulmonary tuberculosis

Speculative: Reduced spontaneous tumour formation; restoration of blood stem-cell differentiation toward mature T cells; slowed development of experimental atherosclerosis

Contraindications

Pregnant or breastfeeding women

Solid-organ or bone-marrow transplant recipients on any maintenance immunosuppression, at any time post-transplant

Active autoimmune disease requiring systemic therapy (systemic lupus erythematosus, rheumatoid arthritis, Graves' disease, multiple sclerosis in relapse)

Immune checkpoint inhibitors, or any prior grade 3 or higher immune-related adverse event

Known hypersensitivity to bovine protein, or a prior reaction to any thymus-derived preparation

Lymphoid malignancy (chronic lymphocytic leukaemia, untreated monoclonal gammopathy of undetermined significance)

Children under 14 years outside the age-banded paediatric doses

Immunoglobulin E-mediated allergic disease severe enough to require an adrenaline autoinjector

Key Interactions

Systemic corticosteroids (prednisone, dexamethasone, methylprednisolone)

Anticoagulants and antiplatelets (warfarin, apixaban, aspirin, enoxaparin)

Biologic disease-modifying drugs (adalimumab, rituximab, tocilizumab)

Oral antihistamines (cetirizine, loratadine)

Non-steroidal anti-inflammatory drugs (ibuprofen, naproxen)

Immunostimulant supplements (echinacea, AHCC, beta-glucans, Trametes versicolor extract)

Zinc and dehydroepiandrosterone

Vitamin D

Melatonin and pineal peptide preparations

Vaccination

Thymus regeneration protocols (growth hormone plus metformin)

Risk & Side Effects

Medium: Hypersensitivity and injection-site reactions

Low: Amplified allergic reactions to co-administered drugs; worsening of autoimmune disease (conflicted)

Speculative: Transmissible agent from bovine source material; contaminated or misidentified grey-market product; acceleration of an occult lymphoid malignancy

Monitoring

Marker	Target	Why
Absolute lymphocyte count	1.8–3.0 ×10⁹/L	The direct target of the drug
Absolute CD4 count	0.6–1.2 ×10⁹/L	Helper T-cell reserve, the subset that rose most in trials
CD4/CD8 ratio	1.5–2.5	Balance between helper and cytotoxic T cells
High-sensitivity C-reactive protein	Below 0.5 mg/L	General inflammatory load
Interleukin-6	Below 2 pg/mL	The cytokine that moved most consistently in the trials
Fibrinogen	200–300 mg/dL	Clotting and inflammation, both reported to shift
D-dimer	Below 0.25 µg/mL fibrinogen-equivalent units	Clot formation and breakdown turnover
Ferritin	50–150 ng/mL	Iron status and an inflammation marker that fell in the trials
Antinuclear antibodies	Negative, titre below 1:40	Screens for silent autoimmunity before stimulating T cells
Thyroid peroxidase antibodies	Below 9 IU/mL	Thyroid autoimmunity is the type most likely to surface under immune stimulation
Total immunoglobulin E	Below 60 IU/mL	The allergic constitution the product information singles out
Erythrocyte sedimentation rate	Below 15 mm/h (men), below 20 mm/h (women)	Inexpensive non-specific inflammation index that fell in the trials

Cadence: Baseline before a first course; immune and inflammatory panel repeated at the end of a 5–10 day course, again at 4–6 weeks, then every 6–12 months where courses are repeated. Autoimmune markers annually, and immediately where joint, skin or thyroid symptoms appear.

Qualitative Assessment

Frequency and duration of upper respiratory infections across a full season compared with the previous year
Time to recover from a minor infection or a skin wound
Daytime energy and exercise tolerance, recorded consistently rather than recalled
New or worsening joint pain, morning stiffness, rash or unexplained fatigue — the pattern that would signal an autoimmune reaction
Local reaction at the injection site: redness, itching or induration (hardened, thickened skin), and whether it grows with successive courses

Thymalin for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment