What the label lists and what reports show
Cobimetinib side effects
Cobimetinib's FDA label: “Most common adverse reactions for COTELLIC (≥20%) are diarrhea, photosensitivity reaction, nausea, pyrexia, and vomiting.” FAERS holds 4,389 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is diarrhoea (441 reports).
- No generic listed
Check it at the source: the cobimetinib FDA label on DailyMed (effective July 29, 2026, Genentech, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of COTELLIC?COTELLIC may cause serious side effects, including: Risk of new skin cancers. COTELLIC may cause new skin cancers (cutaneous squamous cell carcinoma, keratoacanthoma, or basal cell carcinoma). Check your skin regularly and tell your healthcare provider right away if you have any skin changes including: new wart skin sore or reddish bump that bleeds or does not heal change in size or color of a mole Your healthcare provider should check your skin before you start taking COTELLIC, and every 2 months during treatment with COTELLIC. Your healthcare provider may continue to check your skin for 6 months after you stop taking COTELLIC. Your healthcare provider should also check for cancers that may not occur on the skin. Tell your healthcare provider about any new symptoms that develop during treatment with COTELLIC and vemurafenib. Bleeding problems. […]
Source: FDA drug label, Genentech, Inc., effective July 29, 2026 (SPL set c387579e-cee0-4334-bd1e-73f93ac1bde6), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions for COTELLIC (≥20%) are diarrhea, photosensitivity reaction, nausea, pyrexia, and vomiting.
Table 5 Incidence of Adverse Reactions Reported Occurring in ≥15% (All Grades) or Any Percentage (Grade ≥3) in Patients with Histiocytic Neoplasms Treated with COTELLIC in Trial 2
| Body Systems Adverse reactions | All Grades NCI CTCAE v4.0. (%) (n=26) | Grades ≥3 (%) (n=26) |
|---|---|---|
| Diarrhea | 62 | 8 |
| Nausea | 46 | 0 |
| Dyspepsia Gastritis, and gastroesophageal reflux disease. | 27 | 0 |
| Vomiting | 27 | 0 |
| Dry Mouth | 15 | 0 |
| Oral pain Oral dysesthesia and oropharyngeal pain. | 15 | 0 |
| Fatigue Malaise | 42 | 0 |
| Edema Facial edema, edema genital, edema peripheral, periorbital edema, and lymphoedema. | 42 | 4 |
| Pain | 15 | 0 |
| Infections Influenza like illness, mucosal infection, paronychia, pharyngitis, pneumonia,… | 62 | 23 |
| Urinary tract infection | 23 | 8 |
| Pulmonary infections Pneumonia and bronchitis. | 19 | 12 |
| Fall | 15 | 4 |
| Decreased Ejection Fraction | 19 | 12 |
| Acute kidney injury | 15 | 12 |
| Dyspnea | 27 | 15 |
| Cough | 15 | 0 |
| Acneiform dermatitis | 65 | 0 |
| Dry skin | 31 | 0 |
| Maculo-papular rash | 31 | 0 |
| Pruritus | 31 | 4 |
| Hemorrhage Epistaxis, contusion, purpura, hematoma, and rectal hemorrhage. | 19 | 0 |
| Hypertension | 15 | 4 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following adverse reactions are discussed in greater detail in other sections of the label: New Primary Cutaneous Malignancies [see Warnings and Precautions (5.1) ] Hemorrhage [see Warnings and Precautions (5.2) ] Cardiomyopathy [see Warnings and Precautions (5.3) ] Serious Dermatologic Reactions [see Warnings and Precautions (5.4) ] Serous Retinopathy and Retinal Vein Occlusion [see Warnings and Precautions (5.5) ] Hepatotoxicity [see Warnings and Precautions (5.6) ] Rhabdomyolysis [see Warnings and Precautions (5.7) ] Severe Photosensitivity [see Warnings and Precautions (5.8) ] Unresectable or Metastatic Melanoma: Most common adverse reactions for COTELLIC (≥20%) are diarrhea, photosensitivity reaction, nausea, pyrexia, and vomiting. The most common (≥5%) Grade 3-4 laboratory abnormalities are increased GGT, increased CPK, hypophosphatemia, increased ALT, lymphopenia, increased AST, increased alkaline phosphatase, hyponatremia. ( 6.1 ) Histiocytic neoplasms: Most common adverse reactions (≥20%) are acneiform dermatitis, diarrhea, infection, fatigue, nausea, edema, dry skin, maculopapular rash, pruritus, dyspepsia, vomiting, dyspnea and urinary tract infections.
Source: FDA drug label, Genentech, Inc., effective July 29, 2026 (SPL set c387579e-cee0-4334-bd1e-73f93ac1bde6), via openFDA; the full label on DailyMed
What do FAERS reports show?
4,389 reports list cobimetinib among the medicines taken, each a report of something that happened, not proof the medicine caused it; 579 are coded as a death and 2,000 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 13 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Cobimetinib: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions