Medicine (MD/DO)
Immunosuppressants & Antineoplastic Agents
Fluorouracil (5-FU)

Master Fluorouracil (5-FU) with Picmonic for Medicine

With Picmonic, facts become pictures. We've taken what the science shows - image mnemonics work - but we've boosted the effectiveness by building and associating memorable characters, interesting audio stories, and built-in quizzing.

Fluorouracil (5-FU)

Recommended Picmonics

picmonic thumbnail
Prednisone (Glucocorticoids)
picmonic thumbnail
Cyclosporine (Sandimmune) Overview
picmonic thumbnail
Cyclosporine (Sandimmune) Side Effects
picmonic thumbnail
Tacrolimus (Prograf) Overview
picmonic thumbnail
Tacrolimus (Prograf) Side Effects

Fluorouracil (5-FU)

Fluorouracil, or 5-FU, is an antimetabolite medication which works by inhibiting thymidylate synthase, leading to decreased DNA synthesis. This drug is used for slow-growing solid tumors, and is co-administered with leucovorin to treat gastric adenocarcinoma. It is also used topically to treat basal cell carcinoma. Side effects include myelosuppression, severe diarrhea and mucositis. Myelosuppression is not reversible with leucovorin, as it is with methotrexate.

Fluorouracil is an antimetabolite, as it interferes with the cell’s normal metabolic functioning, inhibiting DNA synthesis. It is a pyramidine analog which competes with thymidylate synthetase to inhibit DNA synthesis.

"Thymine-less Death"
Broken Thyme-Thymine causing Death

Fluorouracil is a pyramidine analog that causes a "thymine-less death" in cells. This is because it decreases thymidine monophosphate (dTMP), as 5-FU competes with deoxyuridine monophosphate (dUMP) for thymidylate synthase, inhibiting its action. Fluorouracil is converted to 5-FdUMP, which competes for thymidylate synthetase. This leads to blocked synthesis of the pyrimidine thymidine, which is a nucleoside required for DNA synthesis and replication. Without DNA synthesis, tumor cells undergo apoptosis.

Slow-growing Solid Tumors
Slow-snail Tumor-guy

This medication is indicated for treating slowly-growing solid tumors, with examples of stomach, colorectal, breast, ovarian, and pancreatic cancers.

Co-administered with Leucovorin for Stomach Cancer
Combined with Luke-vulture against Stomach Tumor-guy

Leucovorin is a drug that potentiates the activity of 5-fluorouracil (5-FU). 5-FU takes its active form as FdUMP, which then binds and inhibits the enzyme thymidylate synthase, but has a very short half-life. Leucovorin is a reduced folate, which helps with the 5-FU activity, dubbing it a "chemoprotectant." This combination is used to treat stomach and colorectal cancer.

Basal Cell Carcinoma (Topical)
Bass-guitar Car-gnome

5-FU interferes with the ability of abnormal cells to grow on the skin's top layer. It is indicated for topical administration to treat superficial basal cell carcinomas (BCCs). It is also used for actinic keratosis, superficial squamous cell cancers, and Bowen's disease.

Suppressed Red and White blood cells

This medication causes myelosuppression, leading to anemia (megaloblastic), neutropenia and thrombocytopenia. Unlike with methotrexate, this myelosuppression is not reversible with Leucovorin.


There is a high rate of the development of mucositis with 5-fluorouracil. These are defined as inflammatory lesions of the mucosa, and patients develop oral, nasal and alimentary tract mucositis.

Severe Diarrhea
Severed Toilet

Due to the severe gastrointestinal mucositis that is a side effect of 5-FU, patients can develop severe diarrhea. This is typically dose related, and is very common amongst patients.


Take the Fluorouracil (5-FU) Quiz

Picmonic's rapid review multiple-choice quiz allows you to assess your knowledge.

It's worth every penny

Our Story Mnemonics Increase Mastery and Retention

Memorize facts with phonetic mnemonics

Unforgettable characters with concise but impactful videos (2-4 min each)

Memorize facts with phonetic mnemonics

Ace Your Medicine (MD/DO) Classes & Exams with Picmonic:

Over 1,900,000 students use Picmonic’s picture mnemonics to improve knowledge, retention, and exam performance.

Choose the #1 Medicine (MD/DO) student study app.

Picmonic for Medicine (MD/DO) covers information that is relevant to your entire Medicine (MD/DO) education. Whether you’re studying for your classes or getting ready to conquer the USMLE Step 1, USMLE Step 2 CK, COMLEX Level 1, or COMLEX Level 2, we’re here to help.

Works better than traditional Medicine (MD/DO) flashcards.

Research shows that students who use Picmonic see a 331% improvement in memory retention and a 50% improvement in test scores.