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Published on: 3/5/2026
Gum swelling at the back of the mouth is often due to pericoronitis, an infection around a partially erupted wisdom tooth, with medically approved care that includes professional cleaning, pain relievers, antibiotics only when there are signs of spreading infection, and possible wisdom tooth removal for recurrences.
There are several factors to consider that can change your next steps, and red flags like fever, facial or jaw swelling, difficulty opening the mouth, or trouble swallowing need prompt care, so see the complete guidance below to understand what to do now and how to prevent it from coming back.
If you're dealing with swollen, painful gums at the back of your mouth, pericoronitis may be the cause. This common dental condition affects the gum tissue around a partially erupted tooth — most often a wisdom tooth.
While pericoronitis is usually manageable, it can become serious if ignored. The good news? With the right care and timely treatment, most people recover quickly.
Below is a clear, medically grounded guide to understanding pericoronitis, why it happens, and what to do next.
Pericoronitis is inflammation and infection of the gum tissue surrounding a partially erupted tooth. It most commonly affects lower wisdom teeth (third molars) because they often do not fully break through the gum.
When a tooth only partially erupts, a flap of gum tissue (called an operculum) can remain over it. Food particles, bacteria, and debris easily get trapped under this flap, creating an ideal environment for infection.
Pericoronitis is most common in:
Swelling happens because bacteria become trapped beneath the gum flap. Your immune system responds with inflammation to fight the infection.
Common causes of pericoronitis include:
When bacteria multiply, the gum becomes red, swollen, and painful. Without treatment, the infection can spread.
Symptoms can range from mild to severe. Early pericoronitis may feel like simple gum irritation. More advanced cases can cause significant discomfort.
If you experience fever, facial swelling, or difficulty swallowing, seek medical or dental care immediately. These can signal spreading infection.
Most cases of pericoronitis are localized and treatable. However, untreated infection can spread into surrounding tissues of the face and neck.
In rare but serious situations, infection can lead to:
This is uncommon — but it is why prompt treatment matters.
If you're experiencing any of these symptoms and want to understand what might be causing them, Ubie's free AI-powered gum problems symptom checker can help you assess your condition and guide your next steps before seeing a healthcare professional.
A dentist diagnoses pericoronitis through:
X-rays are important because they help determine whether the wisdom tooth is likely to erupt properly or remain partially trapped.
Treatment depends on the severity of the infection.
For mild cases, a dentist may:
This alone may resolve early pericoronitis.
Antibiotics are prescribed if:
Commonly prescribed antibiotics may include amoxicillin or metronidazole, depending on clinical judgment. Antibiotics control infection but do not fix the underlying problem if the tooth remains partially erupted.
Always take antibiotics exactly as prescribed.
Pain can often be managed with:
Avoid placing aspirin directly on the gum — it can burn the tissue.
If pericoronitis keeps coming back, your dentist may recommend extraction of the wisdom tooth.
Removal is often the most effective long-term solution when:
Extraction is a common and generally safe procedure performed by a dentist or oral surgeon.
If symptoms are mild and you're waiting to see a dentist, you can:
Do not try to cut the gum flap yourself. Do not ignore worsening symptoms.
Home care may reduce discomfort, but it is not a substitute for professional evaluation.
With proper treatment, mild pericoronitis can improve within a few days.
However:
That's why many dental professionals recommend evaluating wisdom teeth before repeated infections occur.
You cannot always prevent pericoronitis, but you can reduce risk by:
If you know you have partially erupted wisdom teeth, regular monitoring is important.
Seek prompt care if you experience:
While most cases are manageable, infections in the mouth can spread quickly in rare cases. If anything feels severe or rapidly worsening, speak to a doctor immediately.
Pericoronitis is a common infection of the gum around partially erupted wisdom teeth. It usually starts with swelling and pain at the back of the mouth due to trapped bacteria.
Most cases improve with:
It's treatable — but not something to ignore.
If you're uncertain whether your symptoms match pericoronitis or could be something else, try using a free AI-powered gum problems symptom checker to get personalized insights about your condition and help determine whether you need to see a healthcare professional right away.
Most importantly, speak to a dentist or doctor about persistent, severe, or spreading symptoms. Early care prevents complications and helps you get back to feeling normal quickly.
(References)
* Bouloukaki I, Lytou I, Merkourea S. Pericoronitis: Current Concepts on Etiology, Diagnosis, and Management. Curr Oral Health Rep. 2023 Dec;10(4):255-263. doi: 10.1007/s40496-023-00344-w. Epub 2023 Nov 10. PMID: 38047023.
* El Amrani B, Zouaoui L, Jaafar M, Chkoura R, El Kholti A, Mokhtari A. Pericoronitis: Etiology, diagnosis, and management. J Clin Exp Dent. 2022 Dec 1;14(12):e1017-e1022. doi: 10.4317/jced.60096. PMID: 36569145; PMCID: PMC9775330.
* Sahoo PK, Routray S, Debnath K. Management of acute pericoronitis: An updated review. J Oral Maxillofac Surg Med Pathol. 2021 Mar;33(2):162-167. doi: 10.1016/j.ajoms.2020.10.007. Epub 2020 Oct 17. PMID: 33796338.
* Singh A, Singh D, Bhatia R, Nayak B. Microorganisms associated with pericoronitis in impacted mandibular third molars: a systematic review. J Oral Maxillofac Surg Med Pathol. 2020 Jan;32(1):17-23. doi: 10.1016/j.ajoms.2019.06.002. Epub 2019 Aug 12. PMID: 32015949.
* Mehra P, Singh J. Pericoronitis. [Updated 2023 Aug 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560636/
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