Ayurveda suggests cleansing two times/year: in fall, during the transition (Ritusandhi) between Pitta & Vata season, and in spring, in the gap between Vata Season & Kapha Season.
Over the months of late spring & summer (Pitta season), fire & water–the hallmarks of Pitta dosha–accumulate (which is why you might feel intense, irritable, angry, while experiencing symptoms of overheating like rashes & heartburn) and now need to be flushed out of the system.
Fall also represents a transition in the seasons, from the high heat of summer to the frigid cold of winter, and because we are inseparable from nature and from her influence, we are supported by her in making a transition within our own bodies, minds and lives at this time.
Fall marks a time that is less intense weather-wise, being neither too hot nor too cold, which makes it more supportive to send the body into a state of intentional, controlled (and healthy) depletion. Partaking in a cleanse and other practices that are catabolic, or Langhana (reducing), in their effects can be far too harsh and invasive for most during the intensity of winter and summer.
Summer is also a very active time of socializing, celebrating, parties, travelling, vacations, and indulging, making it too busy of a time to cleanse. Safe and effective cleansing requires that we slow down and become more present with ourselves, and more alive in presenceful being, rather than the 'doing' energy that Pitta Dosha inspires within us during summer.
Less intensive detoxification needs to occur (for most) during a fall cleanse, while more focus needs to be placed on rejuvenation (to prepare for the cold, dry, light months to come), due to Pitta's tendency to burn up toxicity already. So we cleanse some of the left-over Pitta as well as Ama (toxins), and balance Vata Dosha.
SO WHAT CAN YOU DO TO CLEANSE THIS FALL?
Support the building of Rasa Dhatu (the first tissue) by eating things like dates, cashews, milk, ghee & shatavari or ashwagandha
Drink only warm liquids, like CCF Tea (equal parts cumin, coriander & fennel seeds steeped in hot water)
Practice restorative yoga postures, likes legs up the wall (with a pillow propped underneath your low back). Practice deep restoration by taking a few days off of work entirely (if possible)