Is Tonsillitis Contagious When On Antibiotics?

When our tonsils (the lymph nodes at the back of our throat) get infected, it is known as tonsillitis. Tonsils are a part of our immune system, and when they get infected they can become inflamed, making them quite uncomfortable.

By itself, tonsillitis is not contagious, but the viral or bacterial agents that cause it could be. If the infection is bacterial, it could potentially be treated with antibiotics. 

This article will investigate tonsillitis by examining what it is and what causes it, as well as diagnosis and treatment. Most importantly, how contagious is the condition, and is it contagious if you are taking antibiotics?

What is tonsillitis?

Blausen 0860 Tonsils&Throat Anatomy.png *Image credit by CC BY 3.0, Link

Tonsillitis is an infection at the back of the throat that causes the tonsils to become inflamed. Often this is a common childhood illness, but it can occur in teenagers and adults. To understand why this infection occurs, we must first understand what tonsils are. 

Tonsils are two small masses that are situated at the back of the throat. They are known as lymphoid organs and are part of the immune system. They can initiate the immune response to pathogens that might be ingested or inhaled.

As such, they can recognise pathogens due to specific particles known as antigens and signal to immune cells to fight the infection. It has been shown that they can produce immune cells known as T cells which are normally produced in the thymus.1 This is under normal physiological conditions. However, with tonsillitis, these glands become inflamed and enlarged.

What are the signs & symptoms of tonsillitis?

As the tonsils are in your throat, most of the symptoms present around this area. The condition can feel similar to having the flu or a bad cold. One of the most noticeable symptoms is the appearance of the tonsils, they will likely be red and swollen. Other symptoms include:

  • Sore throat
  • Problems with swallowing
  • A high temperature of 38oC or above
  • Coughing
  • Headache
  • Feeling nauseous
  • Earache
  • Feeling tired

If the condition is particularly severe, the symptoms can exacerbate and include:

  • Swollen, painful glands in your neck (this will feel like there’s a lump on the side of your neck)
  • White pus-filled spots on your tonsils (that will be spotted during examination by the doctor)
  • Bad breath

These symptoms are easily noticeable and will usually last 3 to 4 days. They are quite uncomfortable, especially in the case where the tonsils enlarge to a point of causing difficulty with breathing and swallowing. In this case, more severe treatment would be opted for, which will be explained later in this article.

Is tonsillitis contagious?

Tonsillitis itself is not contagious, but the infections that cause it are. A number of infectious agents can cause the disease, which will be listed in the next section. For example, the common cold, an airborne disease that can cause tonsillitis, can be contagious via coughing. 

Is tonsillitis still contagious when on antibiotics?

When antibiotics are given, it decreases the pool of bacteria that is in your system. This means you will have a smaller amount of bacteria that you could potentially pass on to someone else. Indeed, the NHS states that you are no longer considered infectious after 24 hours of taking antibiotics. However, to be completely sure, you should complete the full course of antibiotics before you consider yourself completely non-contagious. 

What causes tonsillitis?

There are two main causes of tonsillitis, viral and bacterial. The viral causes include double-stranded DNA viruses (Adenoviruses, Epstein Barr virus), single-stranded DNA viruses (Human Boca virus), single-stranded RNA viruses (the flu or coronaviruses) and retroviruses. The most common of these is likely the flu or the common cold.

The bacterial causes are not as common, but one bacteria that can cause tonsillitis is streptococci, which commonly causes the condition known as strep throat.2

Differences between viral and bacterial tonsillitis 

Viruses and bacteria are entirely different forms of life. They have evolved differently and belong to different classes of beings. It is also debatable whether viruses can be classed as alive or not, as they need a host to reproduce.

The most important difference in relation to tonsillitis is that antibiotics can only be administered to bacterial infections.

Antibiotics have no effect on viruses, as they are not designed to fight them. In addition, giving antibiotics needlessly could allow the development of antibiotic-resistant bacteria. 

Diagnosis of tonsillitis

To diagnose tonsilitis, a doctor will examine your symptoms and have a look at the back of your throat. This will then be followed by a swab test to determine if your tonsillitis is caused by bacteria. This is simply a cotton bud that is used to wipe the back of the throat and then sent for laboratory analysis. In addition, a blood test for glandular fever will be performed if the symptoms are severe and not going away. This will confirm that you are suffering from tonsillitis and allow treatment to take place.

Treatment for tonsillitis

Treatment will depend on whether tonsillitis is viral or bacterial in origin. With viral tonsillitis, a doctor will not prescribe anything, and at-home remedies are usually recommended. Tonsillitis will often clear up on its own in 7 to 10 days if the cause is viral.

Home remedies can include:

  • Rest - plenty of rest will allow the body to fight the disease
  • Drink plenty of fluids - keeping the throat moist and hydrated will remove some of the discomfort caused by the condition
  • A saltwater gargle - a solution of salt water can help soothe a sore throat
  • Lozenges - sucking on lozenges helps to soothe the throat
  • NSAIDs - use of ibuprofen can help alleviate the pain or fever associated with tonsillitis

In the case of bacterial tonsilitis, your doctor can prescribe a course of antibiotics. This helps your body fight the infection, meaning you will recover quicker and be uncomfortable for a shorter period of time.

The most common method of treatment is a 10-day course of penicillin. It is important that you take the full course of antibiotics even if the symptoms go away. This is because even if you feel better, there can still be bacteria left over that can build up again to continue the condition. It can even spread to other parts of the body and cause rheumatic fever. This practice can also contribute to the development of antibiotic-resistant bacteria. In addition, if you are allergic to penicillin, you will be prescribed another antibiotic.

If the tonsillitis is very severe, you might need to undergo surgery to remove the tonsils. This usually happens when the tonsillitis is recurring or the bacterial infection doesn’t respond to antibiotics. It is especially important if you have difficulty breathing.


There are several steps you can take to try to avoid getting tonsillitis:

  • As the condition is caused by a virus or bacteria, you should wash your hands to limit the likelihood of infection.
  • Keep a distance from someone with tonsillitis and avoid sharing anything with them, such as cutlery. While tonsillitis is not contagious itself, it is generally a good idea to limit contact.
  • Cover your mouth when you sneeze or cough.

Complications of tonsilitis

It is very rare that there are complications from tonsillitis, but if there are, they are likely due to a bacterial infection. Often it is the result of the infection spreading to another part of the body. The complications can include:

  • A middle ear infection - the fluid in between the eardrum and the inner ear becomes infected by bacteria.
  • Quinsy - An abscess that forms around the tonsils as the infection spreads from the tonsils to the surrounding area.
  • Obstructive sleep apnoea - the walls of the throat become relaxed leading to difficulties breathing while asleep.

When to see a doctor

You should see a doctor if tonsillitis develops and your throat becomes severely sore. They will be able to assess if it is caused by bacteria and prescribe you antibiotics to deal with the condition if it is. They can suggest other treatments as well, even if it is not caused by bacteria.


Tonsillitis is a condition where the tonsils become inflamed and painful. This is due to infection by either a virus or bacteria. The difference between these two causes is that only bacterial infections can be treated with antibiotics. In addition, antibiotics may limit how contagious the tonsillitis is, even within 24 hours, according to the NHS. 


  1. McClory S, et al. Evidence for a stepwise program of extrathymic T cell development within the human tonsil. J Clin Inest. 2012; 122(4): 1403-1415
  2. Windfuhr JP, Toepfner N, Steffen G, Waldfahrer F, Berner R. Clinical practice guideline: Tonsillitis I. Diagnostics and nonsurgical management. Head and Neck. 2016; 273: 973-987.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Miles Peter Bremridge

Masters of Science - MSc Neuroscience Student and Neurosoc Chair, The University of Manchester, England

Miles Bremridge is a MSc Neuroscience Student who is working as a Neurosoc UoM Social Secretary at The University of Manchester. He is also an experienced Medical Writer.

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