 [ Symptoms ] sometimes i black out and eat a whole cake should i be worried this has been happening a lot recently [ Disease ] if i had the list of prescriptions you are taking now perhaps i could be of more help amphetamines are in a class of drug called sympathomimetic amines and some decongestants like pseudoephedrine and even some combination cold medicines can cause a false positive result some over the counter weight loss medications often contain them just give the list to your doctor and have himher figure it out if you have not been taking any amphetamines then just have the test repeated