platelet count went down; This case was reported by a consumer via call center representative and described the occurrence of platelet count decreased in a 69-year-old female patient who received Herpes zoster (Shingrix) for prophylaxis.   Co-suspect products included cephalexin (Keflex) unknown for cellulitis, rituximab (Rituxan) for product used for unknown indication, Flu Seasonal QIV Dresden (Influenza vaccine Quadrivalent 2021-2022 season) for prophylaxis and COVID-19 VACCINE for prophylaxis.   The patient's past medical history included splenectomy (spleen taken out twice (it grew back) and was growing back again) and guillain barre syndrome (Family History) (patient's sister had Guillain-Barre syndrome). Previously administered products included Rituxan (prior infusions with Rituxan). Concurrent medical conditions included immune thrombocytopenia (diagnosed 40 years ago platelet count went down), diabetes and cellulitis (cellulitis of the leg).   In October 2021, the patient received the 1st dose of Shingrix. In September 2021, the patient started Keflex at an unknown dose and frequency. In December 2021, the patient started Rituxan at an unknown dose and frequency. On an unknown date, the patient received Influenza vaccine Quadrivalent 2021-2022 season and COVID-19 VACCINE. On an unknown date, less than 3 months after receiving Shingrix and Influenza vaccine Quadrivalent 2021-2022 season and less than 4 months after starting Keflex, the patient experienced platelet count decreased. The patient was treated with dexamethasone. The action taken with Keflex was unknown. The action taken with Rituxan was unknown. On an unknown date, the outcome of the platelet count decreased was not recovered/not resolved.   The reporter considered the platelet count decreased to be unrelated to Shingrix. It was unknown if the reporter considered the platelet count decreased to be related to Keflex and Influenza vaccine Quadrivalent 2021-2022 season.  Additional details were provided as follows: The case was self reported by the patient. On an unknown date, less than 3 months after receiving Covid-19 vaccine and less than a month after receiving Rituxan, the patient experienced platelet count decreased.  The patient received Shingrix and called to check if there were any drug interactions with Shingrix and Rituxan (or dexamethasone).  The patient was now on Rituxan but she was not on Rituxan when she received Shingrix shot and got a Rituxan infusion last week in December and would get one on 2nd January 2022 (Sunday) and then would get 2 more after that. The patient recently received dexamethasone (40 pills in 4 days) to help bring up her platelet count which was low and she wondered if having recently taken dexamethasone could also affect the efficacy of Shingrix 2nd shot. The patient was wondering if she should postpone getting Shingrix 2nd shot until (after her Rituxan Infusions were finished and after the dexamethasone had time to fully exit her system). The reporter also stated that, she was on high doses of antibiotics for 48 days for cellulitis of her leg and thought that might have set off the platelets going downward again because she had this problem a year and a half ago and was on Rituxan and had the Rituxan and platelet count did go up slowly after that and the patient was fine for a year and a half and now all of a sudden the platelet count dropped low again.  The patient did not want anything to affect the platelets. Her doctor said she could go again and take the Shingrix shot but a couple of pharmacists and nurses told her to wait. The patient got the shingles shot (Shingrix) then got the Covid Shot and then got the flu shot (high potency shot for seniors). She did not get the shots on the same day. The reporter stated that, the clinic wanted her to get the pneumonia shot but she declined. The reporter did not attribute the Shingrix for her platelet count going down but I wanted to file the adverse event report just in case. It was unknown if the reporter considered the platelet count decreased to be related to Covid-19 vaccine and Rituxan. GSK note- even though, the patient did not consider Rituxan responsible for decreased platelet count but asked for it's interaction with Shingrix and also onset of decreased platelet count was not provided, Rituxan was kept suspect conservatively.