Steroid Guide

What Is Andriol? Complete Guide to Oral Testosterone Undecanoate

🗓️ Last updated: Sep 14, 2026 ⏱️ 9 min read ✍️ Vinnofit Team

Andriol testosterone undecanoate — Vinnofit complete guide

Andriol is the brand name for testosterone undecanoate in oral capsule form — a prescription medicine used to treat testosterone deficiency in men. This guide covers its formulation, its unusual absorption route through the lymphatic system, its approved indications, the dosage stated on the label, its side effects, and its legal status — without promoting any non-medical use.

What is Andriol?

Andriol — also sold as Andriol Testocaps and, in some markets, Restandol — is testosterone bound to an undecanoate ester, supplied as 40 mg soft gelatin capsules. The hormone is dissolved in an oily vehicle (castor oil with propylene glycol monolaurate) rather than in crystalline form, and that detail is the basis of how the whole drug works.

The key difference from classic oral steroids is that Andriol is not 17-alpha-alkylated — it lacks the chemical modification that makes drugs like methandienone or stanozolol hepatotoxic. Medically it is classed as a testosterone replacement therapy rather than a conventional oral steroid.

This page is pharmacological education only. Andriol is a prescription medicine, and using it outside the supervision of a qualified doctor carries both health and legal risks.

How it works, and why it must be taken with food

Plain testosterone swallowed as a tablet is almost entirely broken down by the liver before it reaches the bloodstream. The long undecanoate ester makes the molecule lipophilic enough to be packaged into the chylomicrons formed while dietary fat is digested, so it travels through the intestinal lymphatic system into circulation, bypassing first-pass liver metabolism, before esterases release free testosterone.

The practical consequence is that absorption depends almost entirely on food. In a study using an 80 mg dose, peak testosterone after a normal meal was roughly 16 times higher than in the fasted state, and a meal containing about 19 g of fat was enough — a higher-fat meal (44 g) added nothing further.

Even so, oral bioavailability is low (around 3% in controlled models) and the drug is relatively short-acting, which is why the label splits the daily dose between morning and evening, each with a meal.

Approved indications

The approved indication is testosterone replacement therapy in adult men with primary or secondary hypogonadism, after the diagnosis is confirmed by clinical symptoms plus two separate blood testosterone measurements.

That covers situations such as testicular loss after orchiectomy, pituitary insufficiency, erectile dysfunction of endocrine origin, and osteoporosis caused by androgen deficiency. Safety and efficacy have not been established in children and adolescents.

Dosage per the product label

The figures below are taken from the approved prescribing information for replacement therapy. Setting a dose for an individual is the prescribing doctor's responsibility:

Phase	Daily dose	Duration
Initial	120–160 mg per day	2–3 weeks
Maintenance	40–120 mg per day	Based on clinical response

Capsules are swallowed whole with a meal, and the daily dose is preferably split in half — morning and evening. Taking more than prescribed tends to cause digestive upset because of the castor oil in the formulation.

Side effects and monitoring

Andriol is easier on the liver than alkylated oral steroids, but it is still exogenous testosterone with all the same systemic effects:

Suppression of natural production: it lowers the pituitary signals to the testes and can reduce sperm production and fertility.
Raised haematocrit: red blood cell count can climb, so periodic blood counts are part of monitoring.
Cardiovascular: shifts in blood lipids and blood pressure in some users.
Androgenic effects: acne, oilier skin, and acceleration of male pattern baldness in those genetically predisposed.
Gynecomastia: from aromatisation of part of the dose into oestrogen.
Prostate: requires screening and follow-up, particularly in older men.
Digestive upset: nausea or loose stools linked to the castor oil vehicle.

Contraindications: known or suspected prostate or breast cancer in men, and pregnancy or breastfeeding. Monitoring typically includes testosterone levels, full blood count, liver function, lipids and PSA.

Why it's rarely used in athletic circles

Despite the familiar name, Andriol is one of the least attractive preparations for non-medical use, for purely pharmacological reasons: bioavailability is very low, absorption swings with meal content, blood levels are unstable across the day, and the cost per effective dose is high compared with alternatives.

Use outside the approved indications — for muscle or performance — is off-label, and stacks hormonal axis suppression and cardiovascular risk on top of legal exposure. You won't find cycle or dosing protocols for that purpose on Vinnofit.

Legal status and counterfeits

In Oman and across the GCC, testosterone and its derivatives are scheduled prescription-only medicines; importing, selling or possessing them without a prescription is a legal offence. Buying outside the pharmacy channel also exposes you to counterfeits whose actual contents differ from the label.

If you're holding a box and unsure of its origin, have the batch number, expiry date and security seal checked at a licensed pharmacy before any use.

Common myths

"Oral means liver-safe": Andriol genuinely isn't 17-alpha-alkylated and doesn't carry the hepatotoxicity associated with other oral steroids — but "easier on the liver" is not "free of side effects." Suppression, haematocrit rise and cardiovascular effects apply regardless of the route.

"It's mild, so no suppression": any exogenous testosterone at a therapeutic dose suppresses natural production to some degree.

"You can take it on an empty stomach like any pill": in practice it is barely absorbed without food, and that is the single most common reason the treatment appears to fail.

Frequently asked questions

Is Andriol bad for the liver?

Far less so than 17-alpha-alkylated oral steroids, because lymphatic absorption bypasses first-pass liver metabolism. Liver function monitoring is still part of standard treatment follow-up.

Why must it be taken with a meal?

Absorption depends on dietary fat forming the chylomicrons that carry it. Fasted, it is barely absorbed at all; a meal containing roughly 19 g of fat is enough.

How does it compare with testosterone injections?

Injections give higher, steadier levels with much less frequent dosing, while Andriol is oral, variably absorbed, and taken twice daily. Which form suits a patient is a medical decision based on the case, preference and monitoring.

Does it affect fertility?

Yes. Exogenous testosterone suppresses the hormonal axis and can reduce sperm production. Anyone planning to have children should raise this with their doctor before starting.

Can it be bought without a prescription?

No. It is prescription-only in Oman and the GCC, and buying from unlicensed sources is both a legal offence and a health risk given how common counterfeits are.