Methotrexate

Methotrexate

What is methotrexate?

Methotrexate is a medication used in the treatment of skin conditions such as psoriasis, eczema, autoimmune blistering diseases and connective tissue diseases. It is also commonly used in the treatment of non dermatological conditions such as inflammatory bowel disease and rheumatoid arthritis. Methotrexate works by reducing the activity of your immune system.

What to expect during methotrexate treatment?

Before starting the medication, your doctor will need to carry out some baseline blood tests to ensure it is safe for you to take methotrexate. Occasionally, other tests may also be required.

Methotrexate does not work straight away. It may be 8 to 10 weeks before you start noticing an improvement in your skin condition.

It is very important to follow your doctor’s instructions carefully when taking methotrexate. You must return for regular follow ups to monitor for side effects and to assess your response to treatment. You will also be required to have regular blood tests to monitor for side effects. These will be more frequent during the first few months of treatment.

What are the potential side effects of methotrexate?

Common side effects include:

  • Nausea, vomiting
  • Loss of appetite
  • Diarrhoea
  • Headaches
  • Tiredness

Less common side effects include:

  • Hair loss
  • Sensitivity to sunlight
  • Skin rashes
  • Abdominal pains
  • Mouth ulcers
  • Lowered resistance to infections

Rare but potentially serious side effects include:

  • Liver toxicity, including liver fibrosis (more likely with prolonged therapy or at high doses)
  • Lung fibrosis
  • Bone marrow suppression which can result in a reduction of red/white blood cells and/or platelets
  • Long term immune suppression can rarely be associated with lymphoma and other cancers
  • Kidney toxicity

How to take Methotrexate?

Methotrexate is available as 2.5 mg and 10 mg tablets and is taken weekly. It must not be taken daily.  It is best to designate a day of the week to take this medication (e.g. Mondays) to avoid confusion.

You may be given folic acid to take to minimise some of the side effects of this drug. There are different ways to take this and your doctor will instruct you as to when and how to take this. Typically, folic acid is not taken on the day of methotrexate dosing.

If you experience significant gastrointestinal symptoms (such as nausea) it may be possible to split the dosing over 12 hours.  You must talk to your doctor before doing this. Taking it at bedtime or with food can also help reduce the nausea. Alternatively, methotrexate can be given as a weekly injection (under the skin or into the muscle).

Precautions while taking methotrexate

Due to its potential effects on the liver, it is advisable to minimise alcohol intake during treatment or preferably avoid it altogether.

You should see your doctor early if you develop an infection during methotrexate treatment. Your prescribing doctor must be informed if you develop mouth ulcers, bleeding gums, nose bleeds, unusual bruising, skin rashes, shortness of breath, persistent fevers/coughs or any other unusual or worrying symptoms.

You should avoid contact with people who have chicken pox or shingles.

Effects on fertility and pregnancy

Methotrexate has been found to affect sperm and reduce sperm count but this is reversible once you stop taking the medication. You should not father a child while on methotrexate.

Methotrexate is a pregnancy category D drug and can cause birth defects. Women of childbearing potential must take reliable contraception during treatment.

Both men and women must continue contraception for 6 months after stopping methotrexate.  Methotrexate does not affect fertility or future pregnancies in the long term.

Methotrexate should not be taken if breastfeeding.

Drug interactions

Methotrexate has a number of drug interactions, some potentially dangerous. You must inform doctors or pharmacists that you are taking methotrexate.

Do not take any new medications including over-the-counter and “herbal”or naturopathic medications without checking with the doctor.  Examples of drugs which can interact with methotrexate include non-steroidal anti-inflammatory medications (aspirin, ibuprofen), certain antibiotics (trimethoprim, bactrim) and gout medications.

Livevaccines such as the yellow fever vaccine cannot be given whilst on methotrexate. Other vaccines such as Fluvax®and Pneumovax®are safe.  It is important to inform the doctor giving you the vaccine/s that you are taking methotrexate.

This information is intended as a guide only. Please refer to the product information leaflet included in the medication pack for more details. 

Further information about methotrexate

https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-05563-3&d=2015060716114622412

http://www.medsafe.govt.nz/profs/datasheet/m/Methoblastintab.pdf

This information has been written by Dr Yin Vun
Updated 11 November 2015

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