There are 14 words that start with 'asth'.
| asthma | astheny |
| asthmas | asthenia |
| asthenic | asthenias |
| asthenics | asthenies |
| asthmatic | asthmatics |
| asthenosphere | asthmatically |
| asthenospheres | asthenospheric |
Note: These 14 words that start with 'asth' are found from the USA & Canada version of the tournament Scrabble word list.