Product Overview
Xeno Laboratories T4 is levothyroxine sodium at 100 micrograms per tablet, the storage form of thyroid hormone that the body converts in tissue into the active version. It is not an anabolic and not a cycle product, and its role in this range is narrower and more medical than anything else on the list: it is the hormone given to people whose own thyroid no longer produces enough of it.
The reason it is judged so differently from the active hormone is the timeline. The half-life runs about six to seven days in a healthy person, longer in hypothyroidism and shorter when the thyroid is overactive, and a stable daily level takes roughly six weeks to establish. That means a blood test taken in the first fortnight says almost nothing, and a dose changed every week chases a moving target. Conversion into the active hormone happens gradually in the tissues, so subjectively there is often nothing to report for the first week or two at all.
Its sports appearance is a borrowed one. Because the same hormone raises metabolic rate when taken above replacement level, it turns up in cutting plans, usually beside the active hormone described on the T3 page or a beta-2 agonist from the Clenbuterol page. That use is squarely outside the approved indication: the labelling carries a formal warning against thyroid hormone for weight reduction, and the discussions around cutting are research notes rather than recommendations.
Dosage Protocol
The rows below are reference steps for the substance and describe replacement use. Nothing here is a prescription, and the correct dose is set by thyroid blood work rather than by bodyweight alone.
| Beginner | 25-50 mcg a day, held four to six weeks before any assessment |
| Intermediate | 50-100 mcg a day, adjusted against TSH and free T4 results |
| Advanced | 100-150 mcg a day only on prescription, near a full replacement amount |
| Female | 25-100 mcg a day by blood work; pregnancy changes the requirement and is a medical question |
| Administration | Oral in the morning on an empty stomach, 30-60 minutes before food |
| Duration | Continuous in replacement therapy; a sports block is short and is not the approved pattern |
Absorption is where users go wrong first. Antacids containing aluminium or magnesium, iron, calcium, soy, large amounts of fibre and milk all reduce how much of the tablet is taken up, and the interval between the dose and the meal matters more than the exact number of minutes. Because the half-life is so long, nothing about the routine shows up in how the user feels the next day, which is why the schedule is followed by the clock and checked by the laboratory.
Suggested Protocols
Three settings describe how the tablet is actually used. The first is its approved purpose, and the other two are the research discussion around body composition, which the sources present as a community topic rather than as guidance.
What to Expect
- Nothing subjective happens in the first one to two weeks, because conversion into the active hormone is gradual.
- A stable concentration takes about six weeks, so blood tests taken sooner are not informative.
- The first assessment window for TSH and free hormone levels is around six to eight weeks on a steady dose.
- An amount that is too high shows up as a faster pulse, a higher body temperature, sweating and anxiety.
- Excess hormone damages through the heart and the bones, with arrhythmia, mineral loss and increased protein breakdown all described.
- Overdose effects can take from six hours to several days to appear, so a wrong dose is not obvious immediately.
Side Effects and Management
Thyroid Recovery and Monitoring
No testosterone-axis recovery step belongs to this tablet, because it does not act on that axis. The system that has to be watched is the thyroid one, since exogenous hormone reduces the pituitary signal that keeps the gland working and recovery after stopping is gradual.
The pages that carry the rest of the picture are T3 for the active hormone, Clenbuterol for the stimulant route, Proviron for androgen support on a course, and Tamox and Clomiphene for the recovery stage that belongs to any anabolic plan.
