Finding the cause can help you keep them away from whatever is upsetting them. This is important in calming an autistic child. Observe your child and try to figure out the triggers for certain behaviors. If a parent or guardian is aware of the child's triggers, they may be able to avoid it. Keep a notebook to record the child's common triggers will help you to prevent triggering meltdowns. You might also consider using a smartphone app to log meltdowns and their causes. Some common triggers for meltdowns in autistic children are changes or disruptions in their normal routine, overstimulation, frustration and communication difficulties. Meltdowns are different from tantrums. Tantrums are thrown on purpose, as a power play, and will stop once you give in. Meltdowns occur when an autistic person becomes so stressed that they cannot control themselves, and they feel powerless and will not stop until it has run its course. When there is a routine to be followed, the child can predict what will happen next. This helps to keep the child calm. Illustrated schedules can help the child visually see the routine for the day or week. If you know that there will be changes to the routine on a given day, make sure you take the time to prepare your child. Talk to them beforehand and communicate these changes clearly and patiently. When introducing your child to a new environment, it best if you do it when there is less stimuli. This means bringing your child at a time when there is less noise or fewer people. Verbal communication is a source of frustration for many autistic children. Talk patiently, respectfully, and enunciate clearly. Avoid shouting or adopting an aggressive tone, as it may worsen the meltdown. If verbal communication is difficult for your child, try communicating through pictures or other forms of AAC. Remember that communication goes both ways. Always listen to your child, and make it clear that you value and respect what they have to say. Ask them questions if you need clarification to prevent frustration-related meltdowns. When your child is upset, you can sometimes calm them down by diverting their attention. Try playing enthusiastically with a favorite toy, watching a favorite video, or listening to a favorite song. If possible, involve their special interests. Distraction won't always work. For example, questions about your sister's rock collections might distract from her fears about getting a flu shot, but it won't fix things if her problem is that her dress seam feels like fire ants on her skin. Once the child is calm again, it is a good idea to talk to them about what made them angry or stimulated them in the first place. Ask them what happened and work together to find ways to prevent it from reoccurring. Your child may be upset because they are hypersensitive and overstimulated. When this happens, it's a good idea to simply bring the child to a different environment, or to change the environment (e.g. turning off loud music), to reduce overstimulation. For example, if your child experiences fluorescent lights as a trigger, it is better to take your child to a room with alternative lighting, rather than forcing the child to put up with it. If the child is in a location where the environment cannot easily be changed, take precautions. For example, you could give your child sunglasses (to prevent hypersensitivity to light) or earplugs (to drown out noise) to wear in public places. Brainstorm precautions with your child. Sometimes, children just need time before they feel ready to re-engage. Try letting them sit for a while to calm down, usually in any area with limited sensory stimuli. Consider safety. Never leave a young child alone and unsupervised, or lock someone in a room. Make sure the child is safe and able to leave if they want. Use a solution-based approach: instead of blaming or punishing your child, talk about ways to prevent meltdowns and better cope with stress. Try talking about: What the child believes caused the meltdown (Listen patiently). How similar situations can be avoided in the future. More effective coping strategies (taking a break, counting, using deep breaths, asking to leave, etc.). An escape plan to end future meltdowns.

Summary:
Figure out what triggered the meltdown. Stick to a routine. Communicate clearly with your child. Distract the child if you suspect the cause is emotional/psychological. Change the child's surroundings. Give your child some space. After the meltdown, discuss it with your child.