Tiromel vs Triyotex vs Novothyral vs Tertroxin: The T3 Brand Alternatives Compared

When Cynomel or Cynoplus becomes unavailable, the same four brand names surface in forum threads within a few replies: Tiromel, Triyotex, Novothyral, Tertroxin. They are offered more or less interchangeably, as though the problem were simply finding a box with thyroid hormone in it.

They are not interchangeable, and the differences are not subtle. Three of the four contain no levothyroxine at all. One has been discontinued in its home market. One is sold in two strengths that differ by a factor of seven and a half, so naming the brand without naming the strength conveys almost nothing. Only one is a genuine T4+T3 combination, and it uses a different ratio from Cynoplus.

This is a specification comparison. The question of which format to move to, and the dose arithmetic for carrying a Cynoplus protocol across, is covered in the Cynoplus alternatives guide.

The Four Brands at a Glance

Two things fall out of that table immediately.

The first is that the T4 column is nearly empty. Anyone replacing Cynoplus with Tiromel, Triyotex or Tertroxin is not replacing Cynoplus. They are dropping the levothyroxine component and continuing on liothyronine alone, which is a different protocol.

The second is that the dose units are all different. 25 mcg, 10 mcg, 75 mcg, 20 mcg. There is no brand in this list where "one tablet" means the same thing as "one tablet" of any other, which makes tablet-count advice actively misleading.

Tiromel

Tiromel is a liothyronine sodium 25 mcg tablet manufactured by Abdi Ibrahim, the largest pharmaceutical company in Turkey, in EU GMP-certified facilities. It is supplied in boxes of 100 tablets.

Of the T3-only options it is the most straightforward substitution for Cynomel specifically, because the strength is identical at 25 mcg per tablet. A researcher running one Cynomel tablet daily is running the same liothyronine dose on one Tiromel tablet daily. The box size differs, which matters only for reorder intervals.

What Tiromel does not do is replace Cynoplus. It has no levothyroxine component. Substituting it for a combination tablet removes the T4 entirely.

Triyotex

Triyotex is a MEDIX product from Mexico, and it is the brand most likely to cause a dosing error, because it is sold in two formats that are not close to each other: 10 mcg tablets in packs of 30, and 75 mcg capsules in packs of 30.

Seventy-five micrograms in a single capsule is a large unit by the standards of this category. It is three times a Cynomel tablet and seven and a half times a Triyotex tablet. Any advice of the form "switch to Triyotex" that does not specify which presentation is being discussed is incomplete to the point of being hazardous, and forum recommendations very often omit it.

Like Tiromel, Triyotex is liothyronine only.

Novothyral

Novothyral is the only genuine T4+T3 combination among the four. It is manufactured by Merck KGaA and contains 100 mcg levothyroxine with 20 mcg liothyronine per tablet, a ratio of 5:1 by weight. It is distributed across a number of European and Latin American markets including Germany, Austria, Switzerland, Poland, Slovakia, Romania and Chile.

One detail that causes confusion in sourcing discussions: in Mexico the same formulation is marketed as Novotiral, at the same 100/20 strength. Researchers searching for Novothyral through Mexican pharmacy channels and finding nothing are often looking for the wrong name rather than an unavailable product.

For someone leaving Cynoplus, Novothyral is the closest branded substitute available, but it is not equivalent. Cynoplus 120/30 delivers 120 mcg T4 and 30 mcg T3 at a 4:1 ratio. Novothyral delivers 100 and 20 at 5:1. Moving between them changes both the total of each hormone and the proportion between them, so the two components have to be recalculated separately rather than scaled together.

Tertroxin

Tertroxin is a 20 mcg liothyronine tablet, marketing authorisation held by Mercury Pharma Group Ltd in the UK. It appears constantly in older forum threads as the UK reference point for T3.

It has been discontinued in the UK. A significant share of the advice recommending it was written while it was still marketed and has simply never been updated, which is a general hazard of taking sourcing guidance from forum archives: the threads persist long after the products in them do.

Tertroxin remains listed in some other markets, including Australia. It is liothyronine only, so like Tiromel and Triyotex it does not replace a combination tablet.

The Excipient Difference Nobody Compares

Brand comparison almost always stops at the active ingredient, on the reasonable-sounding basis that liothyronine sodium is liothyronine sodium. The rest of the tablet is treated as inert filler not worth listing.

It is worth listing, because the fillers are where these products actually differ, and because one of them recurs across the category.

Every brand with a published excipient list contains lactose. That is not a defect, and for most people it is irrelevant at the quantities involved in a tablet this small. But lactose intolerance is common, coeliac and other gastrointestinal conditions are over-represented in thyroid patient populations, and the excipient profile is a variable that brand-level advice systematically ignores.

Novothyral additionally contains gelatin, which is animal-derived and therefore relevant to anyone avoiding animal products for dietary or religious reasons. That is a straightforward disqualifier for some researchers and it appears nowhere in the forum discussion of Novothyral as a Cynoplus substitute.

The wider point is about what "the same drug" means. Two tablets containing an identical quantity of the identical molecule can still differ in disintegration behaviour, in the presence of an excipient a given individual reacts to, and in the manufacturing tolerances applied to content uniformity. The active ingredient is the part that is guaranteed to be the same. It is not the only part that acts.

For research work where the excipient profile is itself a variable to be controlled, formulations built on a minimal matrix, such as the HPMC and microcrystalline cellulose systems used in extended-release preparations, remove several of these unknowns rather than substituting one filler set for another.

The NDT Route Has Its Own Complication

Desiccated thyroid is the other alternative that surfaces in these discussions, and it does contain both hormones, which makes it a more honest substitute for Cynoplus than any T3-only tablet.

There is a live regulatory development that anyone considering it should know about. On 7 August 2025 the US Food and Drug Administration notified manufacturers, importers and distributors of unapproved animal-derived thyroid products, including Armour Thyroid, NP Thyroid and Nature-Throid, of its intent to take enforcement action, citing the absence of FDA review for safety, purity and potency, and variability in those properties. Roughly 1.5 million Americans received desiccated thyroid extract prescriptions in 2024. The agency indicated a twelve-month window for transition to approved products and has said it intends to issue draft guidance describing its compliance priorities.

That does not make desiccated thyroid unavailable everywhere, and the position outside the United States is different. But it does mean that recommending NDT as the stable fallback for a Cynoplus shortage is, as of 2026, recommending a category with its own unresolved supply question. The comparative case for desiccated thyroid against synthetic formulations is covered in the NDT versus slow-release T3 analysis.

Converting Between the Dose Units

Because no two of these products share a tablet strength, tablet-count advice does not survive a brand change. The only durable unit is total daily micrograms of liothyronine.

The "not cleanly divisible" entries are the practical problem with brand switching and they are why researchers end up quartering tablets. A 25 mcg tablet does not produce a 20 mcg dose, and a 20 mcg tablet does not produce a 25 mcg dose, without splitting to a precision that scored tablets do not reliably support.

Splitting a small tablet is not a neutral operation. Content uniformity is specified for the whole tablet, not for fragments of it, and a hormone dosed in micrograms leaves little margin for an uneven break. Where a protocol requires a strength that a given brand cannot produce by whole or half tablets, the more defensible route is a product manufactured at the required strength rather than a brand improvised into it.

Note also that these conversions cover the T3 component only. For anyone moving off Cynoplus, the levothyroxine component has to be calculated separately, and the arithmetic is set out in the Cynoplus alternatives guide.

Equal Micrograms Are Not Equal Effect

There is a tendency in brand-substitution discussion to treat the microgram figure as the whole story, on the reasoning that liothyronine is liothyronine regardless of who pressed the tablet.

The active molecule genuinely is identical. But a cohort study of a forced dose-equivalent levothyroxine brand switch found measurable movement in plasma thyrotropin despite the substituted product being nominally dose-equivalent, which is a useful caution about assuming that a matched milligram figure produces a matched result. Excipients, tablet manufacture and absorption characteristics are not identical across manufacturers even where the active content is.

For research purposes the implication is procedural rather than alarming: a brand switch is a change to the protocol, and should be treated as one, with the assessment interval that implies rather than an assumption of seamless continuity.

What This Leaves

For a researcher whose protocol was built on Cynomel, the T3-only substitutions are genuinely available and Tiromel matches the 25 mcg unit exactly.

For a researcher whose protocol was built on Cynoplus, the position is narrower. Novothyral is the only branded combination among the commonly named alternatives and it is a different ratio. Desiccated thyroid carries the regulatory question described above. The remaining routes are separate levothyroxine and liothyronine preparations dosed to match, which reproduces any ratio at the cost of running two products, or a combination formulation manufactured at the matching strength.

The SRT4+T3-120 slow release T4+T3 is formulated at 120 mcg T4 with 30 mcg T3, holding the Cynoplus 120/30 strength and 4:1 ratio while extending the release window of the T3 component. For separate dosing, T4 levothyroxine at 100 mcg and the slow-release T3 range allow any proportion to be built. The T3 conversion calculator handles the arithmetic where the ratio changes.

The pharmacokinetic argument for extended release over immediate release, which applies equally to all four brands above, is set out in the sustained-release T3 guide.

What the Evidence Establishes, and What It Does Not

Established. The specifications above, verified against manufacturer and pharmacy listings. Tertroxin's discontinuation in the UK. The FDA's August 2025 notification regarding unapproved animal-derived thyroid products. That a forced dose-equivalent brand switch can move plasma thyrotropin.

Contested. Whether T4 plus T3 combination therapy outperforms levothyroxine monotherapy, which remains unresolved and is treated as an open question by the consensus literature cited below, alongside a 2025 systematic review examining liothyronine safety.

Not established. That any of these brands is pharmacologically superior to another at matched dose. That equal micrograms across manufacturers produce equal physiological effect. Supply status beyond the date of writing, which in this category changes without notice.

Frequently Asked Questions

Is Tiromel the same as Cynomel?

Pharmacologically, at the level of the active molecule and strength, yes: both are 25 mcg liothyronine sodium tablets. They differ by manufacturer, market, excipients and box size, Tiromel being supplied in 100-tablet boxes from Abdi Ibrahim in Turkey.

Can Tiromel replace Cynoplus?

No. Tiromel is liothyronine only. Cynoplus is a T4+T3 combination. Substituting one for the other removes the levothyroxine component from the protocol entirely.

What strength is Triyotex?

Both 10 mcg and 75 mcg, depending on presentation: 10 mcg tablets or 75 mcg capsules, in packs of 30. The brand name alone does not identify the dose, and the two differ by a factor of seven and a half.

Is Tertroxin still available?

It has been discontinued in the UK, where Mercury Pharma held the marketing authorisation. It remains listed in some other markets. Much of the advice recommending it predates the discontinuation.

What is the difference between Novothyral and Novotiral?

They are the same 100/20 mcg levothyroxine plus liothyronine formulation under different market names, Novotiral being the name used in Mexico. Searching for the wrong name is a common reason researchers conclude it is unavailable.

Which of these is closest to Cynoplus?

Novothyral, because it is the only genuine combination product among them. It is not equivalent: 100/20 at 5:1 against Cynoplus 120/30 at 4:1, so both hormone totals and the ratio differ.

Does switching brands at the same dose change anything?

It can. A cohort study of a forced dose-equivalent levothyroxine brand switch found measurable change in plasma thyrotropin, so a brand change is best treated as a protocol change rather than a neutral swap, even at matched micrograms.

Is desiccated thyroid a safe fallback?

It is a genuine combination preparation, but as of August 2025 the FDA has notified manufacturers of unapproved animal-derived thyroid products of intended enforcement action, so the category carries an unresolved regulatory question in the United States alongside its long-standing batch-standardisation limitation.

Closing Note

The recurring failure in brand-substitution advice is not that the wrong brand gets recommended. It is that the recommendation is made at the level of the brand name, when the properties that matter are the hormone content, the strength of a single unit, and whether a second hormone is present at all.

Three of the four brands examined here contain no levothyroxine. One is discontinued in its home market. One spans a seven-and-a-half-fold range of dose units under a single name. Any of them may be a reasonable choice for a given protocol, but none of them is a choice that can be made without reading the specification.

All compounds discussed here are research chemicals supplied for laboratory research use only. Nothing in this article is medical advice, a treatment protocol, or a recommendation for human or animal consumption. Thyroid hormone dosing carries genuine cardiovascular risk and the clinical evidence on combination therapy remains actively contested. Supply and regulatory status change without notice and the positions described were current at the date of writing. Researchers should consult the primary literature cited below and appropriate qualified professionals.