Allergy Drops and Mouth Sores: Ulcers and When to Pause
Allergy drops occasionally cause small mouth sores or ulcers from repeated local contact under the tongue. They are usually minor and heal on their own. If you have open sores, mouth wounds, or recent dental work, your provider may have you pause dosing until the tissue heals.
4 peer-reviewed sources
Mouth sores from allergy drops are an uncommon local reaction to repeated contact. They usually heal on their own, but open sores or recent dental work may mean pausing the dose until the mouth heals.
Medically reviewed by Dr. Chet Tharpe, M.D. · Last reviewed June 2026
Key facts
The most common sublingual immunotherapy side effects are local oral reactions such as itching of the mouth, throat, or ears, which typically appear within minutes and ease over the first weeks of treatment.
In a 2024 meta-analysis of 26 studies and 7,827 patients, local reactions to sublingual immunotherapy occurred in about 40.8% of patients.
Systemic reactions to allergy drops are far less common than local ones, reported in fewer than 0.1% of patients in clinical practice.
Local oral reactions to sublingual immunotherapy are usually most noticeable in the first one to two weeks and tend to lessen as the mouth builds tolerance.
Custom liquid allergy drops are not FDA-approved and are used off-label in the United States; the only FDA-approved sublingual immunotherapy products are tablets such as Grastek, Oralair, Ragwitek, and Odactra.
Why Allergy Drops Can Cause Mouth Sores
Allergy drops sit under the tongue every day, so the same mucosa is exposed to the allergen extract repeatedly. In most people this causes only itching, but some develop small mouth sores or ulcers, an uncommon but recognized local reaction. The cause is usually a combination of mild local inflammation and mechanical contact at the dosing site rather than infection. These sores belong to the broad group of local oral reactions seen in sublingual immunotherapy, the category reported by roughly 40.8% of patients in pooled SLIT safety data, though ulcers specifically are far less frequent than simple itching. A particular consideration for this symptom is the state of your mouth before dosing: open sores, cuts, or recent dental work can mean broken mucosa, and providers often advise pausing until that tissue heals so the extract is not applied to a wound. Because the right extract depends on your triggers, an at-home allergy test from Curex is recommended before beginning immunotherapy. Most sores that do appear are minor and self-limited, healing in a matter of days with simple oral care, much like an everyday canker sore. The patterns worth flagging are sores that keep coming back, take much longer than a week to heal, become large or very painful, or arrive with fever, since those go beyond the usual local picture and may point to a separate oral condition that deserves a proper look.
Mouth sores are an uncommon local reaction; broken tissue from sores or dental work is a reason to pause and check with your provider.
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See if allergy drops are right for youMouth Sores, Open Wounds, and Dosing
Mouth sores from allergy drops are usually small, shallow ulcers at or near the under-tongue dosing site, caused by repeated local contact and mild inflammation rather than infection. They tend to be minor and heal within days, much like a common canker sore. The clinical point unique to sores is intact tissue: applying the extract to broken mucosa, such as an open sore, a bitten cheek, or a site of recent dental work or oral surgery, is something providers generally advise against, often recommending a short pause until the area heals. Curex allergy drops, offered at $39/month with insurance or $99/month self-pay, are taken daily as directed by your provider, who can tell you when to hold and when to resume. Allergy drops are compounded at a specialty pharmacy for each patient. The FDA does not review compounded products for safety or efficacy. Sores that are large, spreading, very painful, recurrent, or accompanied by fever are not the typical SLIT pattern and should be evaluated, as they may reflect another oral condition.
When to Worry: Decision Guide
Is your mouth tissue intact, with at most a small healing sore?
Yes
Continue as directed and keep your provider informed about any sores.
No
If yes, pause and check with your provider; if sores are large, painful, or come with fever, get evaluated.
Frequently asked questions
Can allergy drops cause mouth sores?
Yes, though it is uncommon. Because the dose is held under the tongue daily, the repeated local contact and mild inflammation can occasionally lead to small sores or ulcers near the dosing site. They are part of the broad group of local oral reactions seen with sublingual immunotherapy, but ulcers are much less frequent than simple itching. Most are minor, shallow, and heal within a few days, similar to a canker sore. They are generally manageable, but you should let your allergist know, especially if sores keep returning, take a long time to heal, or are large or very painful, since those features are not the usual pattern.
Should I stop allergy drops if I have mouth sores?
It depends on the sores. For a small, healing sore, your provider may have you continue while keeping an eye on it. But if you have open sores, fresh cuts in the mouth, or recent dental work, the under-tongue tissue may be broken, and applying the extract to a wound is generally something providers advise against, so a short pause until the area heals is common. The safest approach is not to decide alone: contact your allergist, who can tell you whether to hold the dose and when it is appropriate to resume so your treatment stays both safe and consistent.
How long do mouth sores from allergy drops take to heal?
Most small mouth sores related to allergy drops heal on their own within a few days to about a week, similar to ordinary canker sores. Gentle oral care, avoiding irritating foods, and keeping the area clean usually support healing. If a sore lingers beyond one to two weeks, keeps coming back, grows larger, or becomes very painful, that goes beyond the typical pattern and should be evaluated, because it may reflect a separate oral condition rather than a SLIT reaction. Your allergist may also adjust how you take the dose to reduce irritation at the site while the tissue recovers.
Can I take allergy drops after dental work?
It is best to ask your provider first. Recent dental work, oral surgery, extractions, or fresh wounds in the mouth can leave broken tissue at or near the under-tongue dosing area. Applying an allergen extract directly to that broken tissue is generally discouraged, so providers often recommend pausing the drops until the mouth has healed. Resuming too early could irritate the site or interfere with healing. Let your allergist know about any planned or recent dental procedures so they can advise on the right window to pause and restart, keeping your treatment safe and on track.
Are mouth sores from allergy drops the same as canker sores?
They look and behave a lot like ordinary canker sores: small, shallow, and tender ulcers that heal within several days. The difference is the trigger. Sores related to allergy drops tend to appear at or near the under-tongue dosing site and reflect repeated local contact and mild inflammation, whereas common canker sores can appear anywhere in the mouth and have many causes, from minor trauma to stress. Because they share appearance, gentle care that helps canker sores, such as avoiding spicy or acidic foods and keeping the area clean, also tends to help here. Recurrent or unusually large or slow-healing sores, though, deserve evaluation rather than self-treatment.
Can holding allergy drops in a different spot reduce mouth sores?
Technique can matter, since repeated contact at one spot is part of why sores form, but you should not change how you take the dose without your provider's input. Allergy drops are meant to be held under the tongue for a set time to work properly, so improvising placement could affect both comfort and the treatment itself. Your allergist may suggest small adjustments, such as how you position the dose or the timing, to ease irritation while keeping the method effective. If sores keep returning despite good oral care, that is a signal to talk with your provider about a tailored approach rather than experimenting on your own.
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Allergy drops are compounded at a specialty pharmacy for each patient, and the FDA does not review compounded products for safety or efficacy.
This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. Content reviewed by board-certified allergists at Curex.
Allergy drops are compounded at a specialty pharmacy for each patient, and the FDA does not review compounded products for safety or efficacy.
The only FDA-approved sublingual immunotherapy products are tablets — Grastek, Oralair, Ragwitek, and Odactra — which are different from Curex drops.