Is it okey to give an 8 years old fluctisone and antihistamine, decongestant at the same time?

YES, If His: Pediatrician prescribes. Fluticasone is a nasal spray which reduces nasal allergy, inside swelling and congestion. Antihistamine/ decongestant is given for cold symptoms, cough- for a short period of time. If you have any question about the treatment, better talk to the prescribing doctor.

For part of the year: In people (of all ages) with significant allergy, nasal steroid medications, such as fluticasone, are the most potent. They are quite safe for children. Non-sedating antihistamines are safe too. Oral decongestants are ok for short periods of time; nasal, no more than 5 days. The nose should be rinsed with saline before fluticasone. If your son needs meds more than 3 months/year, see an allergist.

Should be OK: Combination treatment including fluticasone nasal spray and antihistamine with decongestant is provided for severe allergic rhinitis.

Depends of symptoms: Depending on the severity of symptoms, they can be used together. Antihistamines can provide good relief of symptoms. Nasal steroid are helpful when the antihistamine is not providing as good results as desired. Be careful with the administration of the fluticasone to prevent a bloody nose. I always caution the use of nasal decongestants as they can cause recurrences of the nasal congestion.