The most common side effects of VEMLIDY are: headache; stomach pain; tiredness; cough; nausea; back pain; Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of VEMLIDY. For more information, ask your healthcare provider or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.