GABA supplements won’t work for everyone. If GABA supplements don’t agree with you, you might experience:- Excessive sleepiness- Lightheadedness- Stomach upset and nausea- Headaches- Tingling sensations- Breathing difficultiesGABA supplements might also do the opposite of what you’ve hoped and raise your anxiety, cause stress, or keep you from falling asleep at night. It’s not a common experience, but it can happen. If this is your situation, stop taking the GABA supplement immediately and contact your doctor.