What are the Common Causes of One Swollen Tonsil?

M. West

Tonsils are lymph nodes in the back of the throat that play a role in fighting infections. The most common cause of one swollen tonsil is the common cold virus, but it is sometimes caused by other viral or bacterial infections. The most frequently seen bacterial causative agent is the bacteria that produces strep throat. Tonsils produce white blood cells that fight bacteria and viruses. When they become overwhelmed by an infection, they become swollen and inflamed, causing the condition known as tonsillitis.

A cold, virus, or bacteria can cause a tonsil to swell.
A cold, virus, or bacteria can cause a tonsil to swell.

One swollen tonsil is most frequently noted in children between pre-school age and the mid-teenage years. At times, both tonsils may be swollen, rather than just one. In addition to this symptom, they might experience fever, a sore throat, or headache. Swallowing may be painful and they may speak with a scratchy voice. The tonsils may be red and may contain white or yellow patches.

Tonsils may become overwhelmed with infection during a condition called tonsillitis.
Tonsils may become overwhelmed with infection during a condition called tonsillitis.

A doctor should be consulted when these symptoms are seen, as complications might result from the condition going untreated. Frequent bouts of one swollen tonsil might cause a condition known as sleep apnea, which is the temporary cessation of breathing during sleep. Other complications include the infection spreading to surrounding tissues in the throat, or the breathing pathway becoming completely blocked. In cases where one swollen tonsil is caused by strep throat, the untreated condition may lead to very serious medical disorders.

Swollen tonsils require a doctor's care.
Swollen tonsils require a doctor's care.

If tests show that the one swollen tonsil is caused by a bacterial infection, antibiotics will be prescribed. Depending on the severity of the infection, they may be administered as a shot or in pill form. If pills are prescribed, it is imperative that they be taken the entire recommended period. Sometimes a parent will stop administering the medicine once the symptoms subside. This might result in the infection not being eliminated.

Throat lozenges that contain benzocaine may alleviate the pain of a swollen tonsil.
Throat lozenges that contain benzocaine may alleviate the pain of a swollen tonsil.

Further doctor recommendations for tonsil problems may include drinking plenty of fluids, especially warm ones rather than hot. Gargling with warm saltwater might help. Throat lozenges containing benzocaine might alleviate pain, but should not be used by young children due to the choking potential. The administration of acetaminophen may also help with pain and fever, but a child should never be given aspirin.

Hygienic practices can also help to prevent one swollen tonsil from reoccurring. Children can be trained to wash their hands thoroughly and often, particularly after visiting the restroom or before meals. They should also abstain from sharing food and drinks with others. Instructing a child to sneeze or cough into a tissue or his or her elbow can help prevent the spread of the infection.

Antibiotics may be necessary to clear up a swollen tonsil caused by a bacterial infection.
Antibiotics may be necessary to clear up a swollen tonsil caused by a bacterial infection.

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Discussion Comments


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I'm not sick but I have had some allergies and at random my throat gets itchy and starts to close, it feels like sticky phlegm that I can't cough up. It's weird and a little scary and when I looked at my throat in the mirror I noticed that I have only one very swollen tonsil? I'm a non-smoker non-drinker 35 years old. I was wondering if anyone had any idea what might be going on with me. I feel 100 percent well except for some bone /body aches and some light chest / breast pain but these are not severe.


I had a tiny bit of pain in my tonsil, a couple days ago when I swallowed, but it doesn't hurt any more; it's just the tonsil on my left side is a little swollen. It's not like it's horribly swollen, and it's not hurting, but it's weird that it's swollen. I've had strep throat very, very bad, but that was a long time ago.


I am a 25 year old female. Back in early November, during a vocal lesson, I noticed that my throat felt tired in one spot (the middle of the right side). It did not hurt or feel sore -- it just sort of ached when I would sing or when I would touch the spot.

After I few weeks of this, I looked into my mouth and noticed that my right tonsil is inflamed and slowly noticed I was becoming more and more fatigued. I saw my PCP and they did confirm that the tonsil is swollen, along with a lymph node on my right side (just slightly swollen). I have no fever or any other symptoms. He put me on an antibiotic and that did not work. They referred me to an ENT in mid December, who took a look and said it was probably just a viral infection that needed to pass. He confirmed my right tonsil was inflamed and the left one slightly. The ENT specialist also took a look at my vocal chords and throat and said those were fine.

The ENT also tested me for mono and that came back negative. I drink plenty of water and eat a particularly healthy diet. My symptoms are still the same: inflamed tonsil, my throat still becomes fatigued with frequent singing or talking. Sometimes I get a sharp pain in the back of my tongue on the right side. I still have very limited energy.

So my question is would a virus last this long? Would it be localized in one area of my throat causing it to tire but not be sore? I am just becoming concerned as to why the symptoms have not allayed. Also, I am not sure if this is related, but I started talking Celexa 20mg in early October. That is the only medication that I am on. Thank you.


@Fa5t3r - It's still worth keeping an eye on them, particularly if one tonsil is swollen. Some people seem to get tonsil infections at the drop of a hat (I'm definitely one of them) and if I see tonsil stones I try to gargle with mouthwash for a while to keep myself from developing an infection.

What I particularly don't like is that I can feel it at the back of my throat when I swallow, as though I've got something caught there. I wish there was a way to prevent this, but I think the only real option is having your tonsils removed.


If you've got one tonsil that seems to have a white spot or two on it, and you aren't sore or anything, you probably don't need to panic.

The first time I noticed this I was really scared that I had cancer or something.

Even though I don't smoke, I've heard of people developing throat cancer spontaneously and that you are supposed to look for white spots.

But, after looking up pictures online, I realized that I had tonsil stones and not cancer. It's basically a little bit of food getting caught in the spongy area of your tonsil and maybe getting a tiny bit infected, but generally not causing any problems until it falls out again.

If you're still worried, you can go and get it checked by a doctor, but they will usually be quite dismissive of it.


It is really unnerving to see infected tonsils, especially if you aren't feeling all that sick. The first time I had them, I thought I just had a normal sore throat infection and it didn't really feel all that bad. But the tonsils were bright red with white blotches all over them and looked really scary.

The only good thing was that it prompted me to go to the doctor and get some antibiotics, because they were really sore by the next day and I'm glad I didn't have to suffer from that any longer than necessary.

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