Why do I have red bumps on the back of my tongue?

The back of everyone's tongue is bumpy. There is a V-shaped row of large circumvallate papillae, leaf-like foliate papillae on the back edges, and pebbly lymphoid tissue (the lingual tonsil) at the base. Our guide to lumps on the back of the tongue explains that anatomy.

What usually changes is the color. These tissues have a rich blood supply, so when they are inflamed they turn bright red and look bigger, which is when most people notice them. The question is less "why are there bumps?" and more "what is irritating them, and is it clearing up?"

• Irritated papillae. Transient lingual papillitis can cause small sore red bumps on the back of the tongue as well as the tip and sides, usually for a few days. Hot drinks, spicy or acidic food, and harsh mouthwash are common triggers.
• A burn. Gulping a hot drink can redden and swell papillae all the way back. Cleveland Clinic notes most tongue burns are superficial and heal in one to three days.
• A sore throat or tonsillitis. When the back of the mouth is infected, the whole area tends to look red and swollen. The NHS lists sore throat, trouble swallowing, fever and swollen neck glands as typical tonsillitis symptoms, usually improving in 3 to 4 days.
• Scarlet fever (strep). The NHS describes a white coating on the tongue that peels to leave it red, swollen and covered in little bumps, called strawberry tongue, along with a sore throat, fever and a rough, sandpaper-like rash. It needs antibiotics from a doctor.
• Hand, foot and mouth disease. Mostly in young children: sore throat and fever, then painful mouth ulcers and spots on the hands and feet.

A few sexually transmitted infections can show up at the back of the mouth. They are much less common than the causes above, but worth knowing about because they need specific testing and treatment:

• HPV. Low-risk HPV types can cause oral warts and papillomas. An AAFP photo quiz describes oral warts as single or multiple smooth, dome-shaped or stalked bumps, usually painless, that can reach the mouth through oral-genital contact. They are removed by a clinician.
• Syphilis. The NHS notes syphilis can cause sores in the mouth early on and white patches in the mouth later, often with few other symptoms. A blood test confirms it and it is treated with antibiotics.
• Herpes. HSV can cause groups of small blisters that break into painful sores. MedlinePlus notes HSV-2, usually genital, can be spread to the mouth during oral sex.

If you have a new partner and develop red bumps or sores at the back of the mouth that do not fit an obvious cold or burn, a sexual health clinic or doctor can test for these without judgment.

Red patches deserve more caution than red bumps. Cleveland Clinic notes that erythroplakia, a red patch with no obvious cause, is usually precancerous or cancerous, and the AAFP recommends biopsy for any such patch. Cancer at the base of the tongue counts as oropharyngeal cancer, which Cleveland Clinic says is most often caused by HPV and can show up as a sore throat that does not get better, pain on swallowing, a lump at the back of the mouth or in the neck, ear pain, or unexplained weight loss.

That is uncommon, and most red bumps fade within days. The practical rule: if redness at the back of your tongue is not clearly improving after 2 weeks, or is only on one side, book an appointment with a doctor, dentist or ENT specialist, who can look at the base of the tongue with a mirror or small camera.

• Gargle with warm salt water (adults only; the NHS advises young children should not gargle).
• Drink cool fluids and choose soft, bland food.
• Skip alcohol, smoking, spicy food and very hot drinks until the redness settles.
• Take paracetamol (acetaminophen) or ibuprofen for pain if needed, following the label.
• Keep tongue cleaning to the front and middle. Pushing a scraper or brush onto inflamed tissue at the back makes it sorer and can set off your gag reflex.