Some people have no symptoms or ones that are so mild, they don’t notice them. Older adults with mono will usually have a fever … Swollen lymph nodes in your neck and armpits 5. About half of those who have mononucleosis have enlargement of the spleen sometime during the course of their illness. Other symptoms include the following: In addition to these symptoms, the spleen (an abdominal organ that stores and filters blood) may become enlarged. Headache 7. Most people who get mono feel better in about 2 to 4 weeks. extreme tiredness, or fatigue a high fever a headache body aches and muscle weakness a red, sore throat swollen glands in the neck or underarms an enlarged spleen rash Mono in adults Mono mostly affects people in their teens and 20s. An adult with mono will experience the same symptoms that a child or teenager will experience, including fever, sore throat, swollen lymph nodes and tonsils, headaches, lack of energy and loss of appetite. Swollen tonsils 6. You may need any of the following: A blood test may show signs of infection or the virus that causes mono. A healthcare provider will rub a cotton swab against the back of your throat. Fever 4. Signs and symptoms of mononucleosis may include: 1. He or she will look for signs such as swollen lymph nodes, tonsils, liver or spleen, and consider how these signs relate to the symptoms you describe. Skin rash 8. Your healthcare provider will ask about your symptoms and examine you. Sore throat, perhaps misdiagnosed as strep throat, that doesn't get better after treatment with antibiotics 3. Adult symptoms of mono include an overwhelming feeling of fatigue. A throat swab may be needed to check for infection. It occurs less commonly in adults over the age of 30. Symptoms may develop slowly and may not all occur at the same time.These symptoms include: 1. extreme fatigue 2. fever 3. sore throat 4. head and body aches 5. swollen lymph nodes in the neck and armpits 6. swollen liver or spleen or both 7. rashEnlarged spleen and a swollen liver are less common symptoms. How is mono diagnosed? The most common symptoms of mononucleosis are fever, sore throat, and swollen lymph glands in the neck, under the arms, and in the groin area. Your doctor may suspect mononucleosis based on your signs and symptoms, how long they've lasted and a physical examination. For some people, … Soft, swollen spleenThe virus has an incubation period of approximately four to six weeks, although in young children this period may be shorter. Typical symptoms of infectious mononucleosis usually appear four to six weeks after you get infected with EBV. The incubation periodthe time it takes symptoms to appear after a person becomes infecte… Fatigue 2. It can take as long as months for your energy to come back completely.