Causes of Swollen Groin Lymph Nodes

The lymph nodes of the groin, or inguinal lymph nodes, are located in the crease between the leg and pelvis. There are two types of inguinal lymph nodes – superficial and deep. They often swell due to an infection or cancer in the areas from which they drain lymph (lymphatic fluid). For this reason, swelling of the groin lymph nodes is an important clinical indication of pathology within the lower abdominal wall, legs, groin, buttocks, anus, perineum and external genitalia.

Anatomy of Inguinal (Groin) Lymph Nodes

Lymph nodes are located throughout the body with each group being responsible for draining a particular area. The common lymph nodes that swell are found in the neck (cervical), armpit (axillary), and groin (inguinal), as well as in numerous other areas of the body.

There are about 10 lymph nodes that collectively form the group known as the superficial lymph nodes. They drain the skin and subcutaneous tissue (which lies just beneath the skin) of the lower abdominal wall below the level of the umbilicus, gluteal region (buttocks), perineum, lower part of anus, external genital organs and the leg.

The superficial lymph nodes themselves drain into the deep inguinal lymph nodes. There are about 3 to 5 of these deep inguinal lymph nodes which filter the lymph and return it to the circulation.

Causes of Enlargement of Inguinal Lymph Nodes


Infections of the leg or genitals may cause swelling of the lymph nodes in the groin. Systemic infections may also cause lymph node swelling of the three main groups – groin, neck or armpits.

  • Sexually transmitted diseases (STDs) such as syphilis, gonococcal infection, chancroid, herpes simplex, lymphogranuloma venereum (LGV) may cause swelling of the inguinal lymph nodes.
  • Bubonic plague caused by Yersinia pestis, may cause extremely tender lymph node enlargement in the groin, accompanied by redness and inflammation of the overlying skin. Lymph nodes of the armpit and neck may also be involved.
  • Viral infections such as infectious mononucleosis may affect the whole body and cause generalized lymph node swelling in various parts of the body, such as neck, armpit or groin.
  • Bacterial infections of the skin and subcutaneous tissue, muscles and bone of the leg or pelvis may also cause swelling of the groin lymph nodes.
  • Toxoplasmosis caused by the parasite Toxoplasma gondii may also result in swollen lymph nodes. Most people do not exhibit any signs or symptoms of the disease and no treatment may be necessary but in babies born to infected mothers or in immunocompromised patients such as those with HIV/AIDS, it can turn into a serious infection. Flu-like symptoms such as body ache, headache, fever, fatigue and sore throat may be accompanied by enlarged lymph nodes.

Cancer and Tumors

Many forms of cancer occurring within the area drained by the groin lymph nodes will lead to swelling (lymphadenopathy). Lymph node swelling usually occurs due to malignant tumors.

  • Leukemia is the cancer of the body’s blood forming tissues, including bone marrow and lymphatic system.
  • Lymphoma is the cancer of the lymph node. It usually starts in the lymph node and may spread to other parts of the body. It may involve groups of lymph nodes in various parts of the body.  There are two types of lymphomas – Hodgkin’s disease and Non-Hodgkin’s disease.
  • Pelvic malignancy (cancer) and metastasis (spread) from cancer of anus or vulva may result in swollen lymph nodes, not related to a lymphoma. Lymph node enlargement developing in a known case of cancer will indicate its spread. If it develops in a case already treated for cancer, it will indicate recurrence of the disease.
  • Melanoma is one of the types of skin cancer which may cause swelling of the lymph nodes around the affected area.

Drugs and Vaccines

  • Medication. The side effects of certain drugs may cause lymph node enlargement although this is not a common occurrence. Some drugs that may contribute towards lymph node swelling include certain medicines for gout (like allopurinol),  epilepsy and bipolar disorder (like phenytoin and carbamazepine), infections like penicillin for bacterial infections and pyrimethamine for malaria and sulfonamides (sulfa drugs). Lymph node enlargement due to drugs is more likely to be generalized.
  • Certain vaccinations such as MMR (measles, mumps and rubella) and typhoid vaccination may also cause generalized lymph node enlargement.


  • Patients with known systemic diseases such as rheumatoid arthritis, sarcoidosis or systemic lupus erythematosus (SLE/SLE) may develop a swollen lymph nodes later in the disease. It is usually generalized.
  • Lymphadenitis or inflammation of the lymph nodes resulting in swelling of the nodes is common in children and is often due to a local or generalized infection, usually viral in origin.  Tuberculous lymphadenitis may be seen more often in developing countries, with generalized lymph node enlargement indicating widespread dissemination of the disease.

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  • samba Kamara

    i am presently experincing a swollen groin lymph nodes. please help me with advice to overcome this swollen.

  • Dr. Chris

    Hi Samba

    You need to consult with a doctor as to the possible cause. It could be related to a persistent infection like a sexually transmitted disease (STD) or cancer. Lymph node swelling in most cases is just a sign of some other underlying disorder. Your doctor will be able to make a diagnosis after considering all your symptoms together or may need to do a biopsy.

  • Sara

    hey dr i need yur help im a 15teen year old girl n im aslo experincing a swollen ass node the node is persent on lower side of aas it pains alot…plz name this dieases n im afarid of telling my mom….
    plz reccomend some medicines

  • Dr. Chris

    Hi Sara

    A swollen lymph node on the buttock could be due to a variety of reasons and I cannot diagnose the cause online ie. name the disease. It depends on how long it has been persisting and if it has been increasing or decreasing in size as well as other signs and symptoms. First you have to ensure that this is a lymph node and not a boil on the ‘bum’. This may account for the severe pain that you are experiencing. You should tell your mom about it and she will take you to see a doctor. Do not interfere with the node or boil as you can make it worse than it is at the moment. Do no try to self medicate either without your doctor’s advice.

  • elrav

    I am a 45 year old female with a history of VIN III and I am post menopause. I have just recently found a hard immobile lump, believe it to be a lymph node, in the inguinal region on the left side. I went for an ultrasound but still don’t have the results back. My concern is because of my history that this could be indicative of some sort of cancer. What follow-up testing should I insist on if the ultrasound is inconclusive? To add to this, I have also been having issues with painful intercourse, along with a bit of bleeding afterwards. My gyn is treating me with a progesterone cream, as he believes it is due to a lack of hormones. Could this also be another sign of pelvic cancer of some sort?

  • Dr. Chris

    Hi Elrav

    Yes, pain and bleeding after intercourse could be related to pelvic cancer. Vaginal dryness and atrophy are also common causes so a progesterone cream is often used.

    If the ultrasound is inconclusive, your doctor will consider a biopsy.

  • VanNostrand

    I have an extremely painful egg sized cyst in the crease of my left leg next to my scrotum. I have a smaller one, grape size, on the left side, which seems to be deeper and feels solid and is not painful.
    I lost my left testi about 11 years ago, after it had swollen to the size of a softball. The doctor had no reason for it other than I had a small amount of mump antibodies in my blood, but I didn’t have the mumps.
    Last year I had a 4cm cancerous polyp removed from my colon.
    Can all of these things be connected to my current problem?

  • Dr. Chris

    Hi VanNostrand

    It is very possible that it is related. Your should ensure that it is a cyst and not due to metastasis (cancer spread) from the original site. your conditions could be related to certain infectious diseases like HIV as well. Other than that I would not want to comment further but I advise that you see a doctor about this problem and do leave it.

  • Sandra

    I am a 54 year old female. I have just had lymphatic drainage done by my massage therapist who noticed that the lymph gland in my right groin is much more enlarged than my left groin. My Dr has also ordered blood tests to investigate my extreme tiredness, but thinks that it is related to menopause and is talking about HRT. Should I also mention the swollen gland to him.

  • Dr. Chris

    Hi Sandra

    Lymph nodes, especially of the neck, armpit and groin, may become temporarily enlarged for various reasons and often this may be due to any serious cause. If the node is constantly swollen, or increasing in size, has become hard or rubbery, then definitely it needs to be investigated. You should monitor the lymph node and report it to your doctor if there any such changes. The question is whether you have felt this enlarged node as well or was it only picked up by your massage therapist. If you are uncertain and need some reassurance that this is not something more serious, then speak to your doctor about it.

  • harrybell

    hi doc,i ve been experiencing swellings around my genitals and of recent i had some swellings in the groin.could it be asign of hiv?pliz help

  • Pankaj

    i am 21 yr old medical student.i hav bilateral inguinal lymphadenopathy since 10 months.4 nodes on lt side 2-3 cm and 2 node on right of same size…my ESR nd other blood tests are in normal limit.i had FNAC 8 months back but it was inconclusive….i am very anxious.tell me what i do?

  • Dr. Chris

    Hi Harrybell

    Yes, it could be a sign of HIV and many other sexually transmitted diseases. It may also be related to other causes, some of which are non-infectious but this cannot be ascertained without further examination. If you are concerned about HIV specifically, take a look at this article on First Signs of HIV.

  • Dr. Chris

    Hi Pankaj

    I would advise repeating the FNAC 6 months after the first one. Given your age and bilateral LAD, STD’s always come into question. Take note of any rash, discharge, warts or ulcers. Also make note of any folliculitis around the pubic hair.

    You should see a urologist at this point. It is possible that it is not due to an infectious cause but nevertheless it must first be excluded given the sexual behavior in your age group. An HIV test is definitely necessary. The size of the nodes and the duration are a cause for concern and therefore you need specialist attention.

  • margie

    hi doc

    i have bean like thing near my anus and another one in my genitals which i believe are lymph nodes. in the past, i just ignored it cause after a few weeks it just go out naturally. but it has been recurring and it makes me worried. what could be the diseases associated with these? what shall i do?

  • Dr. Chris

    Hi Margie

    Many diseases may be associated with this. Just about any infection may causes these symptoms and STD (sexually transmitted diseases) like gonorrhea need to be considered. Depending on your age and past medical history, other causes, including non-infectious causes, may be a possibility. I would advise that you see a doctor immediately. The condition may be progressing and the by waiting without seeking medical treatment, a host of complications can arise.

  • Rojina

    m 34 years unmaried women .in feb 2008 i feel the small lump in my arm.i did FNAC But result was normal and dr told me it was calcified cyst.he advised me if the pain subsides i need not to do exision of pain was subsided i do not feel to be operated.later i feel pain espcialy in cold from 3 days earlier i feel pain when typin.also pain in litle pain in dat part of sholder and there any dnager im i want to exision of ther any ned to do FNAC ?

  • Dr. Chris

    Hi Rojina

    Yes, an FNAC may be advisable again. However, a range of other tests should be done to try to identify the cause of the swollen lymph node, which may not be obvious by any pathology within the node. Therefore an FNAC may be of little use. A mammogram, HIV test, CBC (complete blood count), MRI of the area and so on all need to be done to exclude other causes. Lymph node swelling may only be a sign of pathology in the area. However, if these are clear, then a FNAC once again should considered and excision advisable (do not wait another 2 years). You need to also verify whether the pain you are currently experiencing is due to your swollen node in the arm. By the way, this article in swollen GROIN nodes, so if you have any enlarged nodes in this region as well, then do an HIV test immediately.

  • leakinhead

    Hello I’ve had a persistant swollen groin lymph node for over 3 years. Sometimes it gets extremely large but hasn’t since I became a vegan. But now its slightly smaller than the size of a egg and is very hard and fixed. I got checked out in the past…no cancer, no infection, also had parasite testing and am clear. No one seems to know what the cause is and I’m at my wits end with this…please help!

  • Dr. Chris

    HI Leakinhead

    You should have had a FNAC (fine needle aspiration and cytology) if you have not already done so. A biopsy may also help in a diagnosis when considered with the other tests that have been done thus far. If no abnormality can be found in the node after conducting these investigations (infection, cancer, fibrosis, blockage), then it is possible that the swelling is occurring as a result of some pathology in the pelvic/perineal area. Speak to your doctor again about other investigations which have not been done as yet. There is no way of telling you what is causing this if you have not done all the necessary investigations.

  • Chandelle

    Hi Dr Chris,

    Hoping you could help me out.

    I have what feels like 2 or 3 deep lumps in my groin where my leg meets my privates.

    I initially had pain after shaving, but left the area alone. The pain remained after 2-3 weeks but on inspection there was no cuts where I may have nicked myself. My underwear pushing against my leg hurt this area even more.

    Upon feeling the area, I noticed 3 small lumps rather DEEP in my leg- each about the size of a pea. They seem to be fixed (ie. I can’t move them), round and very firm. Now I can’t leave them alone! I keep proking & prodding and I’m in fear that it is cancer :(

    Over the past couple of days they have increased in size and now resemble two small marbles. They still have the same consistency and are now rather painful. The skin is not any warmer than usual and not red & inflamed. My guess is tha the lumps are too deep to show anything on the skin anyway.

    I do not feel sick at all, I am very active and fit. I participate in safe sex. I am 23 years old.

    I am scheduled for an ultrasound tomorrow but am terrified that it might show something sinister.

    If you have any ideas as to what this might be, I’d love to hear from you.

    Cheers, Chandelle.

  • Dr. Chris

    Hi Chandelle

    While the possibility of cancer does exist, it is unlikely that the growth of the lymph nodes would be so sudden without any other symptoms having been evident by now. Your age group as well makes it less likely, although it is important to note that previous HPV (human papilloma virus) infection may be a factor in cervical cancer. This could be related to an infection, like folliculitis, after shaving. Visible cuts would not be evident. However, there is always the concern of STD’s among younger sexually active women. While safe sex would reduce the chances of picking up an STI, it does not exclude it altogether. If you are seeing a gynecologist soon (hopefully that is where you are having the ultrasound) then there is no need to worry just yet. Rather let your gynecologist assess it and run further tests before jumping to any conclusions.

  • Sami

    Hi dear Dr. Chris my daughter just turn 3 and she has a lump in her groin area which her doctor said it is just a swollen lymph nod about 1 cm and not to worry. But how I know it is not related something serious? I am worried so much why she didn’t run som tests on her?!

  • Laura

    I had a horrible sore throat and fever and my doctor called me in Penicillin assuming it was strep. After 2 days my sore throat went away. Then my lymph nodes got very swollen and painful all over my body. My lymph nodes have been inflamed and painful the whole ten days on penicillin. I am on my 2nd day now off of penicillin and my lymph nodes seem to be a lot better. It was so painful even by my ears due to the lymph nodes behind and in front. I am hopeful the penicillin was the cause of this. My question is what are the chances it was due to the medication? And if so, why does penicillin affect the lymph nodes and how? Thank you.