Alprim can cause the person to feel overly tired or fatigued. This serious symptom may happen along with other side effects, reports. Methotrexate is a drug used for rheumatoid arthritis, psoriasis and inflammatory bowel disease. It is taken on just one day a week. Accidental daily dosing can cause life. Threatening toxicity. Taking alprim may induce the serious common side effect of jaundice, a problem with the function of the person. A disruption of normal liver function can manifest as a discoloration of the skin and the whites of the eyes.