My husband 29 years old and wants to take viagra (sildenafil) to have experience for once. is it bad for his health?

Shouldn't: Unless he has a medical need (erectile dysfunction), then he should be happy with his own gifts, rather than risk a bad effect of a drug he does not need to be taking. If he does not have a medical reason to be seeing a urologist (incomplete erection, etc.), then the risk of the medicine are not worth it, and there is no additive effect to seek.

Bad idea: Trying a drug "just for the experience" makes as much sense as eating a mushroom to see if it's poisonous. Viagra, (sildenafil) altho widely abused as a performance enhancer, is intended for erectile dysfunction. Like most drugs, viagra (sildenafil) is not without side effects: priapism, vision changes, low blood pressure (especially dangerous if also taking nitrates, Alpha blockers or using "poppers"). Use only if needed.

Not a good idea: Unless there are medical reasons, it's not a good idea. Some people use ed medications to enhance sexual performance even hugh they don't have ed, and this can lead to dependence such that it becomes difficult to perform adequately when not taking the drug.