POM-V Prescription Required Companion Animal

Thiamapet 10 mg/ml Oral Solution for Cats

Active ingredient: Thiamazole

Form

Liquid

Species

Cats

Manufacturer

Ecuphar NV

VMD MA No.

32742/5006

What it's used for

For the stabilisation of hyperthyroidism in cats prior to surgical thyroidectomy. For the long-term treatment of feline hyperthyroidism.

Full indications, dosage and side effects ↓

View official SPC (PDF)

The prescription itself has a price. See what practices near you charge for a consultation and the written prescription fee.

Paying less for Thiamazole

1

Ask your vet for a written prescription

They must provide one on request. Under the CMA Order the fee is capped at £21 from 2027.
2

Fill it at a registered online retailer

The CMA found online pharmacies 50–60% cheaper than practice dispensing on common medicines — typically £200–£300 a year.

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Prescription required

Your vet must provide a written prescription on request. You can then purchase from any licensed online retailer.

Clinical information

Thiamapet 10 mg/ml Oral Solution for Cats — SPC Details

Source: VMD Summary of Product Characteristics (SPC). Last updated 26 Mar 2026.

For the stabilisation of hyperthyroidism in cats prior to surgical thyroidectomy.
For the long-term treatment of feline hyperthyroidism.

Do not use in cats suffering from systemic disease such as primary liver disease or
diabetes mellitus.
Do not use in cats showing signs of autoimmune disease.
Do not use in animals with disorders of white blood cells, such as neutropenia and
lymphopenia.
Do not use in animals with platelet disorders and coagulopathies (particularly
thrombocytopenia).
Do not use in cats with hypersensitivity to thiamazole or to any of the excipients.
Do not use in pregnant and lactating females (refer to section 4.7).

Adverse reactions have been reported following long term control of hyperthyroidism.
In many cases, signs may be mild and transitory and not a reason for withdrawal of
treatment. The more serious effects are mainly reversible when medication is stopped.
Following long-term treatment with thiamazole in rodents, an increased risk of
neoplasia in the thyroid gland has been shown to occur, but no evidence is available
in cats.
Cats:
Uncommon
(1 to 10 animals / 1,000 animals treated):
Vomiting*
Inappetence/anorexia*, lethargy*,
bleeding diathesis and icterus
(associated with hepatopathy)*
Severe pruritus and excoriations of the
head and neck*
Haematological abnormalities
(eosinophilia, lymphocytosis,
neutrophilia, lymphopaenia, slight
leukopaenia, agranulocytosis,
thrombocytopaenia, haemolytic
anaemia)*
Immune-mediated haemolytic
anaemia**
Rare
(1 to 10 animals / 10,000 animals
treated):
Immune-mediated thrombocytopenia**,
serum anti-nuclear antibodies**
Very rare
(<1 animal / 10,000 animals treated,
including isolated reports):
Lymphadenopathy**
*These side effects resolve within 7-45 days after cessation of thiamazole therapy.
**Treatment should be stopped immediately and alternative therapy considered following a
suitable period for recovery.
Reporting adverse events is important. It allows continuous safety monitoring of a
veterinary medicinal product. Reports should be sent, preferably via a veterinarian, to
either the marketing authorisation holder or the national competent authority via the
national reporting system. See also the last section of the package leaflet for contact
details.

In order to enhance stabilisation of the hyperthyroid patient the same feeding and
dosing schedule should be used daily.

Revised: October 2024
AN: 00647/2024

i). Special precautions for use in animals
If more than 10 mg per day is required animals should be monitored particularly
carefully.
Use of the product in cats with renal dysfunction should be subject to careful
risk:benefit assessment by the clinician. Due to the effect thiamazole can have on
reducing the glomerular filtration rate, the effect of therapy on renal function should be
monitored closely as deterioration of an underlying condition may occur.
Haematology must be monitored due to risk of leucopenia or haemolytic anaemia.
Any animal that suddenly appears unwell during therapy, particularly if they are febrile,
should have a blood sample taken for routine haematology and biochemistry.
Neutropenic animals (neutrophil counts <2.5 x 109/l) should be treated with
prophylactic bactericidal antibacterial drugs and supportive therapy.
Please refer to section 4.9 for monitoring instructions.
As thiamazole can cause haemoconcentration, cats should always have access to
drinking water.
ii). Special precautions to be taken by the person administering the veterinary
medicinal product to animals
People with known hypersensitivity (allergy) to thiamazole, glycerol, sorbitol or vanillin
should avoid contact with the veterinary medicinal product. If allergic symptoms
develop, such as a skin rash, swelling of the face, lips or eyes or difficulty in breathing,
you should seek medical attention immediately and show the package leaflet or label
to the doctor.
Thiamazole may cause gastrointestinal disturbances, headache, fever, joint pain,
pruritus (itching) and pancytopaenia (decrease in blood cells and platelets).
To prevent a child consuming the product, do not leave a filled syringe unattended.
Following administration of the product any residual product remaining on the tip of the
dosing syringe should be wiped clean with a tissue. The contaminated tissue should
be immediately disposed of.
The used syringe should be stored with the product in the original carton.
In case of accidental ingestion, seek medical advice immediately and show the
package leaflet or the label to the physician.
This product may cause eye irritation.
Avoid skin and eye exposure, including hand-to-eye and hand-to-mouth contact.
Do not eat, drink or smoke while handling the product or used litter.
Wash hands with soap and water after administration and handling of the product and
cleaning the vomit of, or litter used by, treated animals. Wash any spillages or splatter
from skin immediately.
In case of accidental eye contact, rinse eyes immediately with clean running water. If
irritation develops, seek medical advice.
As thiamazole is a suspected human teratogen, women of child-bearing age
must wear non-permeable single-use gloves when administering the product or
handling the litter/vomit of treated cats.
If you are pregnant, think you may be pregnant or are attempting to conceive,
you should not administer the product or handle the litter/vomit of treated cats.
iii). Other precautions
Not applicable.

Revised: October 2024
AN: 00647/2024

Concurrent treatment with phenobarbital may reduce the clinical efficacy of thiamazole.
Thiamazole is known to reduce the hepatic oxidation of benzimidazole wormers and
may lead to increases in their plasma concentrations when given concurrently.
Thiamazole is immunomodulatory, therefore this should be taken into account when
considering vaccination programmes.

This veterinary medicinal product does not require any special temperature storage
conditions.
Keep the bottle tightly closed.

Revised: October 2024
AN: 00647/2024
4.8 Interaction with other medicinal products and other forms of interaction
Concurrent treatment with phenobarbital may reduce the clinical efficacy of thiamazole.
Thiamazole is known to reduce the hepatic oxidation of benzimidazole wormers and
may lead to increases in their plasma concentrations when given concurrently.
Thiamazole is immunomodulatory, therefore this should be taken into account when
considering vaccination programmes.
4.9 Amount(s) to be administered and administration route
For oral use.
The product should be administered directly into the mouth of the cat. Do not
administer in food as efficacy of the product when administered via this route has not
been established.
For the stabilisation of feline hyperthyroidism prior to surgical thyroidectomy and for
the long term treatment of feline hyperthyroidism, the recommended starting dose is 5
mg of thiamazole (0.5 ml of the product) per day.
The total daily dose should be divided into two and administered morning and evening.
In order to enhance stabilisation of the hyperthyroid patient the same dosing schedule
relative to feeding should be used daily.
Haematology, biochemistry and serum total T4 should be assessed before initiating
treatment and after 3 weeks, 6 weeks, 10 weeks, 20 weeks, and thereafter every 3
months. At each of the recommended monitoring intervals, the dose should be titrated
to effect according to the total T4 and to clinical response to treatment. Standard dose
adjustments should be made in increments of 2.5 mg of thiamazole (0.25 ml of the
product) and the aim should be to achieve the lowest possible dose rate. In cats that
require particularly small dose adjustments, increments of 1.25 mg of thiamazole
(0.125 ml of the product) can be used. If total T4 concentration drops below the lower
end of the reference interval, and particularly if the cat is showing clinical signs of
iatrogenic hypothyroidism (e.g. lethargy, inappetence, weight gain and/or
dermatological signs such as alopecia and dry skin), consideration should be given to
reducing the daily dosage and/or dosing frequency.
If more than 10 mg of thiamazole per day is required animals should be monitored
particularly carefully.
The dose administered should not exceed 20 mg of thiamazole per day.
For long-term treatment of hyperthyroidism, the animal should be treated for life.
4.10 Overdose (symptoms, emergency procedures, antidotes), if necessary
In tolerance studies in young healthy cats, the following dose-related clinical signs
occurred at doses of up to 30 mg thiamazole/animal/day: anorexia, vomiting, lethargy,
pruritus and haematological and biochemical abnormalities such as neutropenia,
lymphopenia, reduced serum potassium and phosphorus levels, increased
magnesium and creatinine levels and the occurrence of anti-nuclear antibodies. At a
dose of 30 mg thiamazole/day some cats showed signs of haemolytic anaemia and
severe clinical deterioration. Some of these signs may also occur in hyperthyroid cats
treated at doses of up to 20 mg thiamazole / day.

Revised: October 2024
AN: 00647/2024
Excessive doses in hyperthyroid cats may result in signs of hypothyroidism. This is
however unlikely, as hypothyroidism is usually corrected by negative feedback
mechanisms. Please refer to Section 4.6: Adverse reactions.
If overdosage occurs, stop treatment and give symptomatic and supportive care.
4.11 Withdrawal period(s)
Not applicable.
5.

This information is sourced from the official Summary of Product Characteristics (SPC) published by the Veterinary Medicines Directorate (VMD). It is provided for informational purposes only and does not replace professional veterinary advice. Always consult your vet before administering any medication.