A swollen lymph node in the neck is a natural response, and is a sign that the immune system is fighting some type of infection or inflammation. A lymph node will typically become swollen and painful in the area where the infection is occurring.
Usually, swollen lymph node in the neck is caused by a cold, flu, or a sore throat.
However these lymph nodes can also be a sign of more serious problem, like cancer, AIDS, tuberculosis, or a tumor, especially if they are completely painless and are accompanied by other symptoms such as muscle pain, night sweats or unexplained weight loss.

Why do I have a swollen lymph node in my neck?
A swollen lymph nodes in the neck can be caused by:
1. Cold and flu
These are the main causes for lumps on the neck. Lymph nodes will often become swollen when the body is fighting viral infections, resulting in lumps in the neck (although they can appear elsewhere in the body). Read more about what can cause swollen lymph nodes.
How to treat: These lumps will usually disappear once the cold or flu has resolved. Check out some home remedies for treating a cold or flu naturally.
2. Dengue
Dengue is an infectious viral disease that can lead to swollen lymph nodes. These lymph nodes become inflamed as the body tries to fight the infection. Read about the symptoms of dengue and how this condition presents.
Other viral infections that can lead to swollen lymph nodes include Zika, Chikungunya and cytomegalovirus.
How to treat: if you suspect you may have dengue, you should consult a general practitioner or infectious disease specialist for assessment and treatment.
Once confirmed, dengue is treated with antipyretic, analgesic and/or antiemetic medications, as well as measures like rest and fluids.
In more severe cases, treatment may involve admission to the hospital for close monitoring, IV fluids and/or blood transfusions.
Also recommended: Dengue Treatment (Classic & Hemorrhagic) tuasaude.com/en/dengue-treatment3. Throat inflammation
Although throat inflammation can happen when you have a flu or respiratory virus, you may also experience swelling with bacterial infections like as tonsillitis or strep throat. In these cases, the lymph nodes in the neck can become reactive and lumps can appear in the region.
In addition to lumps, which usually appear on the sides of the neck, it's also possible to have other symptoms such as a cough, headache, pain with swallowing, fever, earache, and bad breath.
How to treat: You are advised to see your doctor for assessment to assess whether you need an antibiotic for treatment. Learn more about how you can treat a sore throat.
4. Ear infection
Ear infections can present similarly to throat inflammations and can also activate the immune system. Many times, infections can cause lumps around the ear, particularly in the area behind the ears. These lumps are also a sign of reactive lymph nodes trying to fight off infection.
Ear infections are associated with other symptoms such as earache, difficulty hearing, itchiness, or pus.
How to treat: You should see a doctor for assessment and treatment, which may include antibiotics. Generally, the lymph node will disappear when the infection is treated.
5. Autoimmune diseases
Autoimmune diseases, such as lupus, rheumatoid arthritis, and HIV/AIDS will generally affect and weaken the immune system by attacking the body’s defense cells. Damaged defense cells can accumulate in the lymphatic glands causing inflammation and lumps.
Lumps related to autoimmune disease normally appear throughout the body. It's also common to have other symptoms such as muscle pain, nausea, vomiting, and night sweats.
How to treat: If you think you have an autoimmune disease you should go to the doctor to do general tests and start adequate treatment, if necessary.
6. Wounds or bites on the skin
It is easy for bacteria to enter the body and spread through wounds or bites. Once the body detects a foreign invader, the immune system activates to try to attack it. In serious cases, in which there is a large number of micro-organisms, the immune system works excessively and this can lead to lumps appearing near the infected area.
How to treat: Monitor your wound or bite for signs of infection like redness, swelling or intense pain. If any of these emerge, you should see your doctor for treatment.
7. Dental abscess
A swollen lymph node can be caused by a dental abscess, which is characterized by a pus-filled pocket that can grow in the gums.
A dental abscess can present with intense pain, increased tooth sensitivity, fever, changes in tooth color, foul breath, and gum swelling.
How to treat: treatment should be guided by a dentist and will vary depending on the cause of the abscess, location, and severity.
The dentist may drain the abscess to facilitate healing, or perform a root canal to eliminate the infection while preserving the tooth.
The dentist may also prescribe antibiotics and anti-inflammatories to relieve symptoms and prevent worsening.
8. Tuberculous lymphadenitis
Tuberculous lymphadenitis is a bacterial infection caused by Mycobacterium tuberculosis bacteria. This bacteria can spread the lymph nodes in the neck, chest, armpits or groin, and cause symptoms such as swollen lymph nodes in the neck or other areas of the body, a low grade fever, excessive fatigue and night sweats.
How to treat: treatment is guided by a pulmonologist, infectious disease specialist or family doctor and typically involves antibiotics for a minimum period of 6 months, such as rifampicin, isoniazid and ethambutol. In some cases, surgery to remove the swollen lymph node may be recommended.
9. Cancer
Various types of cancer demand a lot of work from the immune system, and therefore it's not uncommon for lumps to appear in several locations of the body. The types of cancer that more often cause lumps are lymphomas and leukemia.
How to treat: When all other causes have been excluded, but the lumps are still present, you may need to do some blood tests, to identify possible tumor markers. Other exams that will also help reach a diagnosis include CT scans and MRIs.
Swollen lymph nodes in children
Just like in adults, a swollen lymph node in a child's neck can emerge due to mild conditions, like a cold, flu, dengue or sore throat.
However, a swollen lymph node in a child's neck can also arise due to more serious conditions, such as an autoimmune disease or cancer.
Therefore, if you notice a swollen lymph node on a child's neck, it is recommended to have the child assessed.