Pemetrexed
Say it: pem-eh-TREX-ed · Brand names: Alimta, Pemfexy, Pemrydi RTU
Pemetrexed is a chemotherapy medicine that blocks folate, a vitamin cancer cells need to make DNA.
What it is
Pemetrexed looks like folate, a B vitamin. It blocks several enzymes that cells need to make DNA. Cancer cells cannot grow and die.
Often used for
- non-small cell lung cancer (non-squamous type)
- mesothelioma
How you get it
Pemetrexed is given through a vein (IV) over about 10 minutes, usually once every 3 weeks. You take folic acid every day and get a vitamin B12 shot about every 9 weeks to lower side effects. You also take a steroid around each dose to prevent rash. Your schedule may be different.
Common side effects and what helps
- Feeling tired. Rest and short walks can help.
- Nausea. Take your anti-nausea medicine as your team tells you.
- Low blood counts, which raise your risk of infection. Wash your hands often.
- Mouth sores. Use a soft toothbrush and gentle rinses.
- Rash or itchy skin. Take your steroid as prescribed and use gentle lotion.
- Poor appetite. Try small meals.
Call your care team right away if you have
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills
- A rash that blisters, peels, or spreads
- Shortness of breath or a new cough
- Passing much less urine than usual
- Mouth sores that keep you from eating or drinking
- Bleeding or bruising that will not stop, black or bloody stools, or blood in your urine
Before you start, tell your team
- If you are pregnant, may become pregnant, or are breastfeeding
- If you have kidney problems
- If you take ibuprofen, naproxen, or other pain relievers called NSAIDs
- If you have had radiation
- All the medicines, vitamins, and herbal products you take
Good to know
- Taking folic acid and vitamin B12 is important. It lowers the risk of serious side effects.
- Your kidneys clear this medicine. You will have blood tests, and your team may tell you when to avoid some pain relievers, such as ibuprofen.
- You will have blood tests to check your blood counts.
- Rarely, it can cause lung inflammation or serious skin reactions.
Questions to ask
- When should I start folic acid and how long do I take it?
- Which pain medicines are safe for me?
- When do I take my steroid?
- How many cycles will I get?
Part of these treatment plans
Side effect guides
- Fatigue (tiredness)
- Nausea and vomiting
- Mouth sores
- Appetite loss and weight loss
- Low white blood cells and infection risk
- Skin rash (including EGFR-inhibitor rash)
Sources
Quick answers
- What is Pemetrexed?
- Pemetrexed is a chemotherapy medicine that blocks folate, a vitamin cancer cells need to make DNA. Brand names: Alimta, Pemfexy, Pemrydi RTU.
- What is Pemetrexed used for?
- non-small cell lung cancer (non-squamous type); mesothelioma.
- How is Pemetrexed given?
- Pemetrexed is given through a vein (IV) over about 10 minutes, usually once every 3 weeks. You take folic acid every day and get a vitamin B12 shot about every 9 weeks to lower side effects. You also take a steroid around each dose to prevent rash. Your schedule may be different.
- What are the common side effects of Pemetrexed?
- Feeling tired. Nausea. Low blood counts, which raise your risk of infection. Mouth sores. Rash or itchy skin. Poor appetite.
- When should I call my care team while taking Pemetrexed?
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills; A rash that blisters, peels, or spreads; Shortness of breath or a new cough; Passing much less urine than usual; Mouth sores that keep you from eating or drinking; Bleeding or bruising that will not stop, black or bloody stools, or blood in your urine.
- Which chemotherapy plans include Pemetrexed?
- Carboplatin, pemetrexed and pembrolizumab.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.