Methotrexate for Arthritis: What to Expect, Side Effects, and Lab Monitoring

What is methotrexate and why is it used for arthritis?

Methotrexate is a disease-modifying antirheumatic drug (DMARD) that calms an overactive immune system. In rheumatoid arthritis and psoriatic arthritis, it reduces joint inflammation, pain, and swelling and helps slow joint damage. It is usually a first-line treatment and is often combined with other medicines, including biologics, when needed.

Methotrexate was first developed as a cancer drug, which is why its name can sound alarming. For arthritis, though, it is used at much lower doses and given only once a week. At these doses it works mainly by quieting inflammatory pathways rather than by killing cells. The American College of Rheumatology (ACR) describes methotrexate as the “anchor drug” for rheumatoid arthritis, and it is also used for psoriatic arthritis, lupus-related arthritis, vasculitis, polymyalgia rheumatica, and other inflammatory conditions.

Its goal is not just symptom relief. By controlling inflammation early, DMARDs like methotrexate help protect joints from erosions and long-term disability. You can read more about how it fits into a full care plan on our pages about rheumatoid arthritis treatment and psoriatic arthritis treatment.

Why is methotrexate for arthritis taken once a week and never daily?

For arthritis, methotrexate is prescribed as a single dose once a week, often as several tablets taken together on the same day. Taking it daily by mistake can cause serious, even life-threatening toxicity, including dangerous drops in blood counts, severe mouth sores, and organ damage. Accidental daily dosing is a well-known medication error.

This is the single most important safety fact about methotrexate. Most medicines are taken every day, so it is easy to fall into a daily routine without thinking. MedlinePlus warns that some people have mistakenly taken methotrexate every day instead of on their weekly schedule, and the U.S. Food and Drug Administration has worked with manufacturers on packaging and labeling changes to reduce these errors.

Simple habits make a big difference:

• Pick one day of the week — for example, “methotrexate Monday” or a weekend day — and keep it consistent.
• Write the day on your calendar or set a weekly phone reminder.
• Keep methotrexate out of a daily pill organizer, or use a clearly separate compartment for its one weekly day.
• If you are hospitalized or see a new doctor, tell them it is a once-weekly medicine.
• If you miss your dose, call your doctor or pharmacist for instructions rather than doubling up.

How long does methotrexate take to work?

Methotrexate works slowly. Many people notice improvement in joint pain and swelling after about 6 to 8 weeks, and full benefit can take up to 3 months or longer. Because of this delay, doctors sometimes use short-term bridge treatments, and the dose may be adjusted over time based on how you respond.

It helps to know this ahead of time so you do not give up too soon. The ACR notes that methotrexate typically begins to help within several weeks and that dose adjustments are common during the first months. Your rheumatologist will check on joint counts, symptoms, and sometimes inflammation markers to judge whether it is working.

If methotrexate alone does not control the disease, it is often continued and combined with another treatment — such as other conventional DMARDs, a biologic, or a targeted synthetic drug — rather than simply replaced. For people with an uncertain diagnosis, our article on seronegative rheumatoid arthritis explains how treatment decisions are made even when blood tests are negative.

What are the common methotrexate side effects?

The most common methotrexate side effects are nausea, stomach upset, tiredness the day after the dose, mouth sores, mild hair thinning, and headache. Most are mild and often improve with folic acid, taking the dose in the evening, or switching to an injection. Less common but more serious effects involve the liver, blood counts, and lungs.

Many people take methotrexate for years with few or no problems. When side effects happen, they often follow a pattern: some people feel “off” or tired for a day after their weekly dose, sometimes described as a methotrexate hangover. Practical adjustments, made with your doctor, can help.

The Arthritis Foundation and MedlinePlus both emphasize reporting new symptoms rather than stopping the medicine on your own. Many side effects can be managed without giving up a medication that is helping your joints.

Why is folic acid prescribed with methotrexate?

Methotrexate interferes with how the body uses folate, a B vitamin. Doctors commonly prescribe folic acid (or sometimes folinic acid) alongside it to reduce side effects such as mouth sores, nausea, and abnormal liver tests. Research shows folic acid lowers these side effects without meaningfully reducing methotrexate’s benefit for arthritis.

Your doctor will tell you how and when to take folic acid; schedules vary, and some prescribers ask you to skip it on methotrexate day. Do not change your folic acid routine or substitute over-the-counter supplements without checking first, because the right product and amount depend on your plan.

What blood tests do you need while taking methotrexate?

Methotrexate requires regular blood tests — typically a complete blood count, liver tests, and kidney function. Tests are done before starting, more frequently during the first few months or after dose changes, and then usually every few months once stable. These checks catch problems early, often before you feel any symptoms.

Before starting, doctors usually check baseline blood counts, liver enzymes, kidney function, and screening tests for hepatitis B and C. Many also review a chest X-ray and your vaccination history. Kidney function matters because methotrexate is cleared by the kidneys; if kidney function drops, the drug can build up.

Lab monitoring is a partnership. Keeping your blood test appointments is part of taking methotrexate safely, just like remembering your weekly dose. If you travel or split time between Houston and elsewhere in Texas, ask whether labs can be drawn at a convenient location and sent to your rheumatologist. Our guide on what to bring to a rheumatology appointment can help you keep results organized.

Can you drink alcohol while taking methotrexate?

Alcohol and methotrexate can both stress the liver, so doctors advise limiting alcohol, and some recommend avoiding it entirely. The safe amount, if any, depends on your liver tests, other health conditions, and your dose. Ask your rheumatologist for a specific limit rather than guessing.

Liver problems from methotrexate are uncommon with proper monitoring, but risk rises with heavy drinking, obesity, diabetes, fatty liver disease, and viral hepatitis. Be honest with your doctor about how much you drink — it helps them set a safe plan rather than judge you.

Is methotrexate safe during pregnancy?

No. Methotrexate can cause miscarriage and serious birth defects, so it must not be taken during pregnancy. Anyone who could become pregnant needs reliable contraception while taking it, and the medicine is usually stopped for a period of months before trying to conceive. Plan pregnancy with your rheumatologist well in advance.

If you think about having children in the next year or two, mention it at your first visit. Several arthritis medicines are considered compatible with pregnancy, and switching ahead of time can keep your disease controlled while protecting the pregnancy. Men taking methotrexate should also discuss family planning with their doctor, as guidance for men differs from guidance for women. If you become pregnant unexpectedly while taking methotrexate, stop taking it and call your doctor right away.

What infection and warning signs should you watch for on methotrexate?

Because methotrexate affects the immune system, report fever, chills, sore throat, a cough that will not go away, painful urination, or a wound that looks infected. Call promptly about new shortness of breath or dry cough, mouth sores, unusual bruising or bleeding, yellowing skin or eyes, dark urine, or very little urine.

Your doctor may ask you to skip a weekly dose during an active infection or around surgery — but only on their instructions. Some antibiotics, especially trimethoprim-sulfamethoxazole, can interact dangerously with methotrexate, so always tell every prescriber and pharmacist that you take it. Live vaccines are generally avoided while on methotrexate, while inactivated vaccines such as the flu shot are usually encouraged; ask your doctor which vaccines you need, ideally before starting.

Where can I get methotrexate care in West Houston, Katy, or Fulshear?

West Houston Arthritis and Rheumatology helps adults start, monitor, and adjust methotrexate and other disease-modifying treatments for rheumatoid arthritis, psoriatic arthritis, and related conditions. The practice is led by Dr. Syed Alam, MD, FACR, a double board-certified rheumatologist, and is accepting new patients.

Dr. Alam is board-certified in internal medicine and rheumatology, completed his rheumatology fellowship at Temple University Hospital and his internal medicine residency at John H. Stroger, Jr. Hospital, and has more than 10 years of rheumatology experience. The office is at 19002 Park Row Blvd, Suite 100, Houston, TX 77084, open Monday through Friday, 8:00 AM to 5:00 PM, and can be reached at (832) 305-5226. The practice accepts most major insurance plans; see our insurance page for details.

Patients come from Katy, Fulshear, Cinco Ranch, Cypress, Richmond, Rosenberg, Sealy, Sugar Land, and West Houston, and patients from elsewhere in Texas may request an appointment. Learn more about rheumatoid arthritis and psoriatic arthritis, or read when to see a rheumatologist.

Key takeaways

• Methotrexate for arthritis is taken once a week, never daily — accidental daily dosing can be dangerous.
• It usually takes 6 to 8 weeks, and sometimes up to 3 months, to work fully.
• Most methotrexate side effects are mild, and folic acid is commonly prescribed to reduce them.
• Regular blood tests for blood counts, liver, and kidney function are a required part of safe treatment.
• Limit alcohol, plan pregnancy in advance, and report fever, new cough, or mouth sores promptly.

Frequently asked questions

What happens if I accidentally take methotrexate two days in a row?

Call your doctor or Poison Control (1-800-222-1222) right away, even if you feel fine. Extra doses can lower blood counts and cause other toxicity, and early treatment can help. Seek emergency care for severe symptoms.

Is methotrexate chemotherapy?

Methotrexate is also used in cancer treatment, but at much higher doses. For arthritis, it is given at low doses once a week and works mainly by calming inflammation, so the side-effect profile is very different.

Is injectable methotrexate better than tablets?

Injectable methotrexate is absorbed more consistently and may cause less nausea for some people. Your doctor may suggest switching if tablets cause stomach upset or are not working well enough.

Will methotrexate make my hair fall out?

Mild hair thinning can happen, but significant hair loss is uncommon at arthritis doses. Folic acid may help. Tell your doctor if you notice thinning so other causes can be checked.

Can I get vaccines while taking methotrexate?

Inactivated vaccines, such as the flu shot, are generally recommended. Live vaccines are usually avoided. Ask your rheumatologist about timing, since some vaccines are best given before starting or around your dose.

How long will I need to take methotrexate?

Many people take methotrexate for years because it controls a long-term condition. If your disease stays in remission, your doctor may discuss carefully lowering the dose. Never stop on your own.

Your next step

Sources and further reading

1. Methotrexate (Rheumatrex, Trexall, Otrexup, Rasuvo), American College of Rheumatology.
2. Methotrexate, MedlinePlus Drug Information.
3. Medication Guides and Patient Labeling Resources, U.S. Food and Drug Administration.
4. Methotrexate Prescribing Information, DailyMed, National Library of Medicine.
5. Methotrexate, Arthritis Foundation.
6. Rheumatoid Arthritis, National Institute of Arthritis and Musculoskeletal and Skin Diseases.
7. Psoriatic Arthritis, National Institute of Arthritis and Musculoskeletal and Skin Diseases.