Mono: Symptoms, the Rapid Mono Test, and How Long It Lasts

Mono (infectious mononucleosis) is usually caused by the Epstein-Barr virus. The classic signs are a very sore throat, fever, swollen glands in the neck and deep tiredness, most often in teens and young adults. A rapid mono test from a finger stick or blood draw can confirm it during a visit. There's no antiviral cure, so treatment is rest, fluids and pain relief. Most people feel better in two to four weeks, but tiredness can linger, and contact sports have to wait because the spleen can swell.

Mono symptoms

• Extreme tiredness
• Sore throat, often severe, sometimes with white patches on swollen tonsils
• Fever
• Swollen lymph nodes in the neck, and sometimes the armpits
• Headache and body aches
• Swollen spleen, felt as fullness or pain in the upper left belly
• Sometimes a rash, especially after taking amoxicillin or ampicillin

Symptoms usually appear four to six weeks after exposure, and they can be mild in young children.

Mono or strep?

Both cause a sore throat with fever and swollen glands, and you can have both at once. Strep usually comes on faster and is treated with antibiotics. Mono lasts longer, causes more tiredness, and antibiotics won't help. A clinician can test for both at the same visit. Our post on the rapid strep test explains that one.

How it spreads

Mono spreads mostly through saliva, which is why it's called "the kissing disease," and also through shared cups, utensils, toothbrushes and vapes. People can spread it for weeks, sometimes months, after symptoms start, and some people carry it with no symptoms at all.

How the mono test works

A rapid mono test checks a few drops of blood for antibodies and gives a result in minutes. It can be negative in the first week of symptoms, so if it's negative and mono still seems likely, a clinician may retest later or send blood work to a lab.

How long does mono last?

• Fever and sore throat usually improve within one to two weeks
• Swollen glands and the spleen shrink over two to four weeks
• Tiredness can last several weeks, and occasionally months

Can you get mono more than once?

Usually not. After an Epstein-Barr infection, the virus stays dormant in your body for life, and you develop immunity. It can reactivate, but that rarely causes symptoms. Getting mono-like illness again is more often a different virus.

What helps

• Rest, and ease back into school, work and activity as energy allows
• Drink plenty of fluids
• Use acetaminophen or ibuprofen for fever, sore throat and aches
• Gargle with salt water and use throat lozenges
• Avoid alcohol while you recover, because the liver can be affected

Avoid contact sports and heavy lifting for at least three to four weeks, or until a clinician clears you. A swollen spleen can rupture with a hit to the belly.

When to get seen

Come in for a sore throat with fever and swollen glands, to check for mono and strep, or if symptoms are dragging on. At an AfterOurs clinic, a standard self-pay visit is $175, a visit with a rapid test such as a mono test is $250, and a self-pay in-clinic visit never costs more than $330. We contract with all major commercial and government plans, including Colorado Medicaid and Medicare. See our mononucleosis page and the cost and insurance page.

Go to the ER or call 911 if you have sudden, sharp pain in the upper left belly (which can be a ruptured spleen), trouble breathing or swallowing, drooling or can't swallow saliva, a stiff neck, confusion, or yellowing of the skin or eyes.

Where to find us

Four clinics across metro Denver, all ages welcome, se habla español:

• Hampden (Southeast Denver): 8 AM–11 PM daily
• Littleton: 8 AM–11 PM daily
• Thornton: 8 AM–11 PM daily
• Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM

Walk in, or book online.