Can I still get lip injections if just my skin develops dermatitis?

Did your dermatologist or injector tell you this was a dermatitis following your injections?  I am not certain the story is quite so simple.  There may have been other factors involved in your reaction following your peri oral injections. I would get some clarification before proceeding with further injections or get a second in person opinion.

Sorry to hear of your previous negative experience. While an allergic reaction following hyaluronic acid fillers is possible, it is rare. Unless you have previously been diagnosed with rosacea and/or present other symptoms, the redness following your filler injections is most likely not caused by rosacea. Dermatitis is a general term used to describe skin irritation. Contact dermatitis describes a negative reaction to a specific irritant or allergen.
You might want to consider getting a second opinion from another reputable provider before trying HA fillers again. If you have any photos of the reaction, bring them into your next visit so that your provider can get a better idea of what might be going on before proceeding.

Hyaluronic acid very rarely can cause an allergy or some form of reaction . I was wondering if it could be lesions due to past labial herpes infection which by the way is something kind of frequent.  Stress, medication like steroids or anything that could lower your immune system could trigger the lesions. In any case we need to make sure that it is hyaluronic acid and nothing different to play safe.