Methotrexate

What is methotrexate?

Methotrexate is a disease-modifying antirheumatic drug (DMARD) and immunosuppressant. It was originally developed to treat cancer. But now, it is now more commonly used in lower doses to manage autoimmune and inflammatory conditions. It achieves this by suppressing the immune system[1].

What is methotrexate used for?

Methotrexate is prescribed to treat a range of conditions, often under specialist supervision, including[1]: 

• Rheumatoid arthritis 

• Psoriasis and psoriatic arthritis 

• Crohn’s disease 

• Systemic lupus erythematosus (SLE) 

• Vasculitis 

• Juvenile idiopathic arthritis 

• Certain types of cancer (in higher doses) 

How does methotrexate work?

Methotrexate works by preventing cell division which leads to immune system suppression, anti-inflammatory actions and autoimmunity, and thus easing symptoms. It also inhibits folic acid metabolism, which slows down the growth of rapidly dividing cells – including immune cells and skin cells involved in certain conditions. This makes it effective for conditions where the immune system is overactive[1]. 

Who can take methotrexate?

Methotrexate is suitable for adults and children when prescribed under specialist care for autoimmune or inflammatory diseases[1]. 

However, it is generally not suitable for people who are pregnant or breastfeeding, or those with liver disease, ascites, significant kidney problems, have severe or active infections, immunodeficiency or significant pleural effusion. It is also unsuitable for individuals with a history of alcohol dependency[1]. 

Please tell your doctor or pharmacist about any conditions you may have before you start treatment, and always follow the instructions in the Patient Information Leaflet[3]. 

What is the typical dosage of methotrexate?

Methotrexate is typically taken once a week on the same day each week. The starting dose is usually between 2.5–15mg, however, will be adjusted based on your response and any side effects. Folic acid is usually prescribed alongside methotrexate to help protect healthy cells and reduce side effects such as nausea and mouth ulcers; however, it is important not to take folic acid on the same day you take methotrexate. Please remember never to take extra doses without medical advice – this can be dangerous[1]. 

How do you take methotrexate?

Methotrexate is available in several forms, such as tablets, oral liquid, or injections. It’s usually taken on the same day once a week, with food to reduce stomach upset. Methotrexate prefilled pens for injection may be used if indicated by your specialist. With methotrexate, it’s important to stick to the weekly schedule as daily use can be harmful[1]. 

Can you stop taking methotrexate suddenly?

You should not stop taking methotrexate suddenly without speaking to your doctor or pharmacist. Stopping may cause your condition to flare up. If you’re doing well on the medication, your doctor  or pharmacist may eventually discuss tapering the dose under close supervision – please follow their advice[1]. 

What should you do if you take too much methotrexate?

Methotrexate overdose is serious. It can cause liver damage and low blood counts (bone marrow suppression), along with severe infections. Seek emergency help immediately if you suspect you’ve taken an overdose. It is important to stick with the dose prescribed by your doctor and only take methotrexate on the same day each week, be aware methotrexate comes in different strengths (2.5mg and 10mg tablets) it is recommended only one strength be prescribed[1].  

What should you do if you forget a dose of methotrexate?

If you forget a dose of methotrexate and it's within 1–2 days of when you should have taken it, you can generally take that dose. However, if it's nearly time for your next dose, skip the missed one. Do not take a double dose. Keeping to a routine is important with methotrexate – to avoid missed doses, use a weekly reminder or medication diary[1]. 

Which medicines should you avoid while taking methotrexate?

Methotrexate may interact with the following[1]: 

• NSAIDs (e.g. ibuprofen) which may increase methotrexate toxicity 

• Penicillin & quinolones (e.g. amoxicillin, ciprofloxacin) which may increase methotrexate toxicity 

• PPIs (e.g. lansoprazole) which decreases the clearance of methotrexate

• Trimethoprim (antibiotic) that can severely lower blood counts 

• Live vaccines which should be avoided due to immune suppression 

• Alcohol which increases the risk of liver damage 

In general, taking methotrexate should be avoided along with these, however, always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[3]. 

What are the side effects of methotrexate?

Some common side effects of methotrexate include nausea or vomiting, general fatigue, mouth ulcers, a loss of appetite, and hair thinning[1]. 

Other serious but less common side effects, for which you should seek medical advice, are[1]: 

• Liver damage 

• Lung problems like a persistent cough or shortness of breath 

• Bone marrow suppression (leading to infections, bleeding, or anaemia) 

• Increased risk of infections 

While taking methotrexate, you will need regular blood tests (usually every 2 to 12 weeks) to check your liver, kidneys, and full blood counts are all healthy. Your doctor may request additional tests before starting treatment or during[1]. 

If any side effects are worrying, severe, or persistent, contact your doctor.

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice.

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[3].

Frequently asked questions about methotrexate

How long does methotrexate take to work? 

When taking methotrexate, you may take up to 6 to 12 weeks to notice improvements in symptoms[1]. 

Can I drink alcohol while taking methotrexate? 

It’s generally best to avoid when taking methotrexate. This is because even small amounts of alcohol can increase the risk of liver damage[1]. 

Can I get pregnant while taking methotrexate? 

Methotrexate can harm an unborn baby. That’s why, for both men and women, it’s important to use reliable contraception and stop methotrexate at least 6 months before trying to conceive[1]. 

Will I need regular check-ups while taking methotrexate? 

Yes, you’ll usually need frequent blood tests while taking methotrexate. This will monitor for liver problems, low blood counts, and kidney function – especially during the first few months of treatment and dosage changes[1]. 

What should I do if I think I have an infection? 

It is important to report all symptoms and signs suggestive of an infection to your doctor when taking methotrexate, especially sore throat, bruising and ulcers[1].  

Do I need to take precautions in the sun when taking methotrexate? 

Yes, methotrexate is known to cause photosensitivity reactions which appear like severe sunburn. It is important to avoid exposure to UV light (including intense sunlight like sunbeds), use high SPF sunscreen and protective clothing. Speak to a healthcare professional if they have concerns about skin reaction[1].  

Can I take methotrexate and folic acid together? 

No, it is important to avoid taking folic acid on the same day a methotrexate as can reduce the efficacy of methotrexate. Taking folic acid 48 hours prior to methotrexate dose may give added protection against gastrointestinal side effects[1]. 

For the official NHS guide to methotrexate, visit their website.